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Journal articles on the topic 'Dynamical tunability'
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1
Sciortino, Alice, Michela Gazzetto, Gianpiero Buscarino, Radian Popescu, Reinhard Schneider, Gaetano Giammona, Dagmar Gerthsen, et al. "Disentangling size effects and spectral inhomogeneity in carbon nanodots by ultrafast dynamical hole-burning." Nanoscale 10, no. 32 (2018): 15317–23. http://dx.doi.org/10.1039/c8nr02953a.
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Wang, Zhao, and Li. "Dynamical Manipulation of Surface Plasmon Polaritons." Applied Sciences 9, no. 16 (August 11, 2019): 3297. http://dx.doi.org/10.3390/app9163297.
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As the fundamental and promising branch of nanophotonics, surface plasmon polaritons (SPP) with the ability of manipulating the electromagnetic field on the subwavelength scale are of interest to a wide spectrum of scientists. Composed of metallic or dielectric structures whose shape and position are carefully engineered on the metal surface, traditional SPP devices are generally static and lack tunability. Dynamical manipulation of SPP is meaningful in both fundamental research and practical applications. In this article, the achievements in dynamical SPP excitation, SPP focusing, SPP vortex, and SPP nondiffracting beams are presented. The mechanisms of dynamical SPP devices are revealed and compared, and future perspectives are discussed.
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Shcherbinin, S. A., S. V. Ustiuzhanina, and A. A. Kistanov. "Dynamical stability and electronic structure of β-phosphorus carbide nanowires." Journal of Micromechanics and Molecular Physics 05, no. 03 (September 2020): 2050007. http://dx.doi.org/10.1142/s2424913020500071.
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In this work, [Formula: see text]-phosphorus carbide 1D nanowires (PCNWs) are investigated in the framework of density functional theory. The dynamical stability of the considered [Formula: see text]-PCNWs at 300[Formula: see text]K is verified using ab initio molecular dynamics calculations. According to the results on the band structure calculations, [Formula: see text]-PCNWs can be semiconductors, semimetals or metals depending on their size and form. Thus, owning to their unique shape and high tunability of electronic properties, [Formula: see text]-PCNWs may be used in optical and photovoltaic nanodevices.
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Huang, G. Q., and Z. W. Xing. "Band-gap tunability and dynamical instability in strained monolayer and bilayer phosphorenes." Journal of Physics: Condensed Matter 27, no. 17 (April 2, 2015): 175006. http://dx.doi.org/10.1088/0953-8984/27/17/175006.
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Bruno, Vincenzo, Stefano Vezzoli, Clayton DeVault, Thomas Roger, Marcello Ferrera, Alexandra Boltasseva, Vladimir M. Shalaev, and Daniele Faccio. "Dynamical Control of Broadband Coherent Absorption in ENZ Films." Micromachines 11, no. 1 (January 20, 2020): 110. http://dx.doi.org/10.3390/mi11010110.
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Interferometric effects between two counter-propagating beams incident on an optical system can lead to a coherent modulation of the absorption of the total electromagnetic radiation with 100% efficiency even in deeply subwavelength structures. Coherent perfect absorption (CPA) rises from a resonant solution of the scattering matrix and often requires engineered optical properties. For instance, thin film CPA benefits from complex nanostructures with suitable resonance, albeit at a loss of operational bandwidth. In this work, we theoretically and experimentally demonstrate a broadband CPA based on light-with-light modulation in epsilon-near-zero (ENZ) subwavelength films. We show that unpatterned ENZ films with different thicknesses exhibit broadband CPA with a near-unity maximum value located at the ENZ wavelength. By using Kerr optical nonlinearities, we dynamically tune the visibility and peak wavelength of the total energy modulation. Our results based on homogeneous thick ENZ media open a route towards on-chip devices that require efficient light absorption and dynamical tunability.
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Basu, Pradosh, Barun Halder, Sriganapathy Raghav, and Utpal Roy. "Nonlinear Excitations in Ultracold Atoms Trapped in Triple Optical Lattices." Condensed Matter 7, no. 3 (September 9, 2022): 52. http://dx.doi.org/10.3390/condmat7030052.
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Various solitary wave excitations are found for a Bose-Einstein condensate in presence of two hybrid potentials in the form of triple mixtures of optical lattices. One of these potentials comprises of a combination of two important lattice profiles, such as frustrated optical lattice and double-well super-lattice, within one. Another represents a composite lattice combination, resulting in a wider and deeper frustrated optical lattice. The dynamical equation for such a system is solved by the exact analytical method to obtain a bright solitary wave, periodic wave and cnoidal wave excitations. We also report Anderson localization, bifurcation of condensate at the center and a competition between two different types of localizations upon trap engineering. Dynamical and structural stability analyses are also carried out, which reveal the obtained solutions as extremely stable for structural noise incorporation and sufficiently stable for dynamical stability. These triple mixtures of optical lattices impart better tunability on the condensate profile, which has made this system a true quantum simulator.
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Sciortino, Cannas, and Messina. "Temperature-Dependence of Solvent-Induced Stokes Shift and Fluorescence Tunability in Carbon Nanodots." C 5, no. 2 (April 24, 2019): 20. http://dx.doi.org/10.3390/c5020020.
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We carried out a cryogenic investigation on the optical properties of carbon dots, aiming to better understand their emission mechanism and the role of the solvent. The solvatochromic Stokes shift is quantified by a low temperature approach which allows freezing of the photo-excited state of carbon dots, preventing any solvation relaxation. Moreover, the reduction in temperature helps to identify the dynamical inhomogeneous contribution to the broadening of the emission band; therefore, disentangling the role of solvent from other types of broadening, such as the homogeneous and the static inhomogeneous contributions.
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Debashis, Punyashloka, Aman K. Maskay, Pramey Upadhyaya, and Zhihong Chen. "Spin–orbit torque controlled stochastic oscillators with synchronization and frequency tunability." Journal of Applied Physics 131, no. 12 (March 28, 2022): 123901. http://dx.doi.org/10.1063/5.0077237.
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Stochastic oscillators based on emerging nanodevices are attractive because of their ultra-low power requirement and the ability to exhibit stochastic resonance, a phenomenon where synchronization to weak input signals is enabled due to ambient noise. In this work, a low barrier nanomagnet-based stochastic oscillator is demonstrated, whose output jumps spontaneously between two states by harnessing the ambient thermal noise, requiring no additional power. By utilizing spin–orbit torque in a three-terminal device configuration, phase synchronization of these oscillators to weak periodic drives of particular frequencies is demonstrated. Experiments are performed to show the tunability of this synchronization frequency by controlling an electrical feedback parameter. The current required for synchronization is more than eight times smaller than that required for the deterministic switching of similar nanomagnetic devices. A model based on Kramers’ transition rate in a symmetric double well potential is adopted and dynamical simulations are performed to explain the experimental results.
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Genix, Anne-Caroline, Vera Bocharova, Bobby Carroll, Philippe Dieudonné-George, Edouard Chauveau, Alexei P. Sokolov, and Julian Oberdisse. "Influence of the Graft Length on Nanocomposite Structure and Interfacial Dynamics." Nanomaterials 13, no. 4 (February 16, 2023): 748. http://dx.doi.org/10.3390/nano13040748.
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Both the dispersion state of nanoparticles (NPs) within polymer nanocomposites (PNCs) and the dynamical state of the polymer altered by the presence of the NP/polymer interfaces have a strong impact on the macroscopic properties of PNCs. In particular, mechanical properties are strongly affected by percolation of hard phases, which may be NP networks, dynamically modified polymer regions, or combinations of both. In this article, the impact on dispersion and dynamics of surface modification of the NPs by short monomethoxysilanes with eight carbons in the alkyl part (C8) is studied. As a function of grafting density and particle content, polymer dynamics is followed by broadband dielectric spectroscopy and analyzed by an interfacial layer model, whereas the particle dispersion is investigated by small-angle X-ray scattering and analyzed by reverse Monte Carlo simulations. NP dispersions are found to be destabilized only at the highest grafting. The interfacial layer formalism allows the clear identification of the volume fraction of interfacial polymer, with its characteristic time. The strongest dynamical slow-down in the polymer is found for unmodified NPs, while grafting weakens this effect progressively. The combination of all three techniques enables a unique measurement of the true thickness of the interfacial layer, which is ca. 5 nm. Finally, the comparison between longer (C18) and shorter (C8) grafts provides unprecedented insight into the efficacy and tunability of surface modification. It is shown that C8-grafting allows for a more progressive tuning, which goes beyond a pure mass effect.
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Feng, Chun, Meiyin Yang, Kui Gong, Xujing Li, Baohe Li, Yong Jiang, and Guanghua Yu. "Dynamical mechanism for coercivity tunability in the electrically controlled FePt perpendicular films with small grain size." Journal of Applied Physics 115, no. 2 (January 14, 2014): 023906. http://dx.doi.org/10.1063/1.4861738.
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Bai, Qiang. "Manifestation of the spontaneous parity-time symmetry breaking phase transition in hot-electron photodetection based on a tri-layered metamaterial." Nanophotonics 8, no. 3 (February 14, 2019): 495–504. http://dx.doi.org/10.1515/nanoph-2018-0207.
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AbstractWe theoretically and numerically demonstrate that the spontaneous parity-time (PT) symmetry breaking phase transition can be realized respectively by using two independent tuning ways in a tri-layered metamaterial that consists of periodic array of metal-semiconductor Schottky junctions. The existence conditions of PT symmetry and its phase transition are obtained by using a theoretical model based on the coupled mode theory. A hot-electron photodetection based on the same tri-layered metamaterial is proposed, which can directly show the spontaneous PT symmetry breaking phase transition in photocurrent and possesses dynamical tunability and switchability. This work extends the concept of PT symmetry into the hot-electron photodetection, enriches the functionality of the metamaterial and the hot-electron device, and has varieties of potential and important applications in optoelectronics, photodetection, photovoltaics, and photocatalytics.
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Ren, Shenqiang. "(Invited) Switching Molecular Ionic Magnetism." ECS Meeting Abstracts MA2022-02, no. 59 (October 9, 2022): 2211. http://dx.doi.org/10.1149/ma2022-02592211mtgabs.
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Magneto-ionics of molecular based magnets, the ionic control of magnetism, promise ultralow-power sensor technologies, while the extent of reversible ion intercalation in turn is also the key state-of-charge feature in rechargeable battery electrodes. Here we report the reversible ion intercalation in molecular magnetic electrode, which simultaneously monitors the state of charge in battery and enables dynamic switching of its room-temperature magnetic transition. Microwave excited spin wave reveals lithiation degree in molecular-magnetic anode, enabling magneto-ionics towards the real-time monitoring of state of charge in rechargeable battery under a low magnetic field and radiofrequency. The structural vacancy and hydrogen-bonding networks in such molecular magneto-ionic compound enables the reversible lithiation and delithiation, which in turn, leads to a dynamical and reversible magnetization tunability.
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Wang, Xuefeng, Qiqi Yang, Ronghua Huan, Zhan Shi, Weiqiu Zhu, Zhuangde Jiang, Zichen Deng, and Xueyong Wei. "Frequency comb in 1:3 internal resonance of coupled micromechanical resonators." Applied Physics Letters 120, no. 17 (April 25, 2022): 173506. http://dx.doi.org/10.1063/5.0091237.
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Frequency comb in microelectromechanical systems has attracted many concerns, which is expected to realize great achievements analogous with the optical frequency comb. Previous frequency combs are generated by mode coupling in a single micro-resonator. To pursuit more excellent tunability and robustness, it is impending to create a frequency comb through another way, i.e., coupled but relatively independent micro-resonators. In this work, a frequency comb in 1:3 internal resonance region of an electrostatically coupled microsystem is reported. We demonstrate the occurrence conditions and its influencing factors of the frequency comb. A dynamical explanation, which has good agreement with the experimental results, is presented to further reveal its intrinsic mechanism. Our finding provides a controllable method to produce a frequency comb that is beneficial to potential applications, such as signal processing and sensing sensitivity enhancement.
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Chen, Chun-Wei, Ting-Mao Feng, Chih-Wei Wu, Tsung-Hsien Lin, and Iam Choon Khoo. "Massive, soft, and tunable chiral photonic crystals for optical polarization manipulation and pulse modulation." Applied Physics Reviews 10, no. 1 (March 2023): 011413. http://dx.doi.org/10.1063/5.0139168.
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Photonic crystals enable modulation of light waves in space, time, and frequency domains; in particular, chiral photonic crystals are uniquely suitable for polarization rotation and switching of complex vector fields. Current development of chiral photonic crystals, nevertheless, are still confronted with limitations of one form or the other such as large optical losses, limited or absence of tunability, narrow operation bandwidth, and/or insufficient optical thickness for practical implementation. In this work, we show that cholesteric liquid crystals as 1D tunable chiral photonic crystals are promising alternatives to not only address all these issues and deficiencies but also enable new photonic applications in wider temporal and spectral realms. Our work entails a detailed study of the dynamical evolution of cholesteric helical self-assembly and defect formation in the bulk of thick cholesteric liquid crystals under various applied electric field conditions and a thorough exploration of how applying fields of vastly different frequencies can eliminate and/or prevent the formation of unremovable defects and to control the alignment of cholesteric helices in the entire bulk. We have developed a dual-frequency field assembly technique that enables robust room-temperature fabrication of stable well-aligned cholesteric liquid crystals to unprecedented thickness (containing thousands of grating periods) demanded by many photonic applications. The resulting chiral photonic crystals exhibit useful much-sought-after capabilities impossible with other existing or developing chiral photonic crystals—compactness (single, flat, millimeter-thick optical element), high transmission, dynamic tunability, large polarization rotation, and various switching/modulation possibilities for ultrafast and continuous-wave lasers in the visible, near- and mid-infrared regimes.
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Singh, Ranjan, Jie Xiong, Abul K. Azad, Hao Yang, Stuart A. Trugman, Q. X. Jia, Antoinette J. Taylor, and Hou-Tong Chen. "Optical tuning and ultrafast dynamics of high-temperature superconducting terahertz metamaterials." Nanophotonics 1, no. 1 (July 1, 2012): 117–23. http://dx.doi.org/10.1515/nanoph-2012-0007.
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AbstractThrough the integration of semiconductors or complex oxides into metal resonators, tunable metamaterials have been achieved by a change of environment using an external stimulus. Metals provide high conductivity to realize a strong resonant response in metamaterials; however, they contribute very little to the tunability. The complex conductivity in high-temperature superconducting films is highly sensitive to external perturbations, which provides new opportunities in achieving tunable metamaterials resulting directly from the resonant elements. Additionally, superconducting metamaterials are expected to enable strong nonlinear response and quantum effects, particularly when Josephson junctions are integrated into the metamaterial resonant elements. Here we demonstrate ultrafast dynamical tuning of resonance in the terahertz (THz) frequency range in YBa2Cu3O7-δ (YBCO) split-ring resonator (SRR) arrays excited by near infrared femtosecond laser pulses. The photoexcitation breaks the superconducting Cooper pairs to create quasiparticles. This dramatically modifies the imaginary part of the complex conductivity and consequently the metamaterial resonance on an ultrafast timescale, although the real conductivity does not change significantly. We observed resonance switching accompanied by substantial frequency tuning as a function of photoexcitation fluence, which also strongly depends on the nanoscale thickness of the superconducting films. All of our experimental results agree with calculations using an analytical model, which takes into account the contributions of the complex conductivity of the YBCO films to SRR resistance and kinetic inductance. The theoretical calculations reveal that the increasing SRR resistance upon increasing photoexcitation fluence is responsible for the reduction of resonance strength, and changes in both the resistance and kinetic inductance cause the resonance frequency shifts.
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Mitra, Srimanta, Aquil Ahmad, Shamik Chakrabarti, Sajib Biswas, and Amal Kumar Das. "Study of structural, electronic and magnetic properties of Ti doped Co2FeGe Heusler alloy: Co2Fe1−x Ti x Ge (x = 0, 0.5, and 0.75)." Journal of Physics: Condensed Matter 34, no. 3 (November 3, 2021): 035803. http://dx.doi.org/10.1088/1361-648x/ac3039.
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Abstract Tunability of structural, magnetic and electronic properties of Co2FeGe Heusler alloy is experimentally demonstrated by doping Ti in the Fe site (i.e. Co2Fe1−x Ti x Ge), followed by in-depth first principle calculations. Co2FeGe in its pure phase shows very high saturation magnetization, Curie temperature and spin-wave stiffness constant which were reported in our earlier work. With gradual increase in Ti doping concentration (x = 0.5 and 0.75), the experimental saturation magnetization is found to be decreased to 4.3 μ B/f.u. and 3.1 μ B/f.u. respectively as compared to the parent alloy (x = 0) having the saturation magnetization of 6.1 μ B/f.u. Variation of spinwave stiffness constant is also studied for different x and found to be decreasing from peak value of 10.4 nm2 meV (for x = 0) to the least value of 2.56 nm2 meV for x = 0.5. Justification of the experimental results is given with first principle calculations. Computational phase diagram of the alloys is found in terms of formation energy showing that the doping in Fe site (i.e. Co2Fe1−x Ti x Ge) is more stable rather than in Co site (i.e. Co2−x FeTi x Ge). The change in magnetic moment and half-metallicity with Ti doping concentration is better explained under GGA + U approach as compared to GGA approach signifying that the electron–electron correlation (U) has a distinct role to play in the alloys. Effect of variation of U for Ti atom is studied and optimized with reference to the experimental results. The dynamical stability of the Co2Fe1−x Ti x Ge alloy crystal structure is explained in terms of phonon dispersion relations and the effect of U on the phonon density of states is also explored. Close agreement between the experimental and theoretical results is observed.
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HARTEMANN, F. V., A. M. TREMAINE, S. G. ANDERSON, C. P. J. BARTY, S. M. BETTS, R. BOOTH, W. J. BROWN, et al. "Characterization of a bright, tunable, ultrafast Compton scattering X-ray source." Laser and Particle Beams 22, no. 3 (July 2004): 221–44. http://dx.doi.org/10.1017/s0263034604223059.
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The Compton scattering of a terawatt-class, femtosecond laser pulse by a high-brightness, relativistic electron beam has been demonstrated as a viable approach toward compact, tunable sources of bright, femtosecond, hard X-ray flashes. The main focus of this article is a detailed description of such a novel X-ray source, namely the PLEIADES (Picosecond Laser–Electron Inter-Action for the Dynamical Evaluation of Structures) facility at Lawrence Livermore National Laboratory. PLEIADES has produced first light at 70 keV, thus enabling critical applications, such as advanced backlighting for the National Ignition Facility andin situtime-resolved studies of high-Zmaterials. To date, the electron beam has been focused down to σx= σy= 27 μm rms, at 57 MeV, with 266 pC of charge, a relative energy spread of 0.2%, a normalized horizontal emittance of 3.5 mm·mrad, a normalized vertical emittance of 11 mm·mrad, and a duration of 3 ps rms. The compressed laser pulse energy at focus is 480 mJ, the pulse duration 54 fs Intensity Full Width at Half-Maximum (IFWHM), and the 1/e2radius 36 μm. Initial X rays produced by head-on collisions between the laser and electron beams at a repetition rate of 10 Hz were captured with a cooled CCD using a CsI scintillator; the peak photon energy was approximately 78 keV, and the observed angular distribution was found to agree very well with three-dimensional codes. The current X-ray dose is 3 × 106photons per pulse, and the inferred peak brightness exceeds 1015photons/(mm2× mrad2× s × 0.1% bandwidth). Spectral measurements using calibrated foils of variable thickness are consistent with theory. Measurements of the X-ray dose as a function of the delay between the laser and electron beams show a 24-ps full width at half maximum (FWHM) window, as predicted by theory, in contrast with a measured timing jitter of 1.2 ps, which contributes to the stability of the source. In addition,K-edge radiographs of a Ta foil obtained at different electron beam energies clearly demonstrate the γ2-tunability of the source and show very good agreement with the theoretical divergence-angle dependence of the X-ray spectrum. Finally, electron bunch shortening experiments using velocity compression have also been performed and durations as short as 300 fs rms have been observed using coherent transition radiation; the corresponding inferred peak X-ray flux approaches 1019photons/s.
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Zhou, Yinning, Zhichao Ma, and Ye Ai. "Dynamically tunable elasto-inertial particle focusing and sorting in microfluidics." Lab on a Chip 20, no. 3 (2020): 568–81. http://dx.doi.org/10.1039/c9lc01071h.
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We explore the use of non-Newtonian viscoelastic fluids to achieve size-tunable elasto-inertial particle focusing and sorting in a microfluidic device, and realize the controllable tunability among three separation thresholds.
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Li, Jianfei, Jingfeng Yao, Chengxun Yuan, Ying Wang, Zhongxiang Zhou, and Jingwen Zhang. "Tunable transmission near Dirac-like point in the designed plasma photonic crystal." Physics of Plasmas 29, no. 3 (March 2022): 033505. http://dx.doi.org/10.1063/5.0079293.
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The ingenious combination of gaseous plasma and alumina columns forms a plasma photonic crystal with the advantage of dynamic tunability to control the transmission of electromagnetic waves. Plasma density as another degree of freedom is used to realize the Dirac-like cone, which degenerates accidentally at the first Brillouin zone in a square lattice. The investigations of transmission spectrum and phase variation demonstrate that the Dirac-like cone formed in a plasma photonic crystal still possess the zero-refractive-index property, and the cloaking effect for obstacles can be turned on or off by adjusting the electron density. Based on the feature of dynamic tunability, the dual-channel optical switch is designed, and the transmission path of electromagnetic waves can be controlled dynamically.
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Haefner, Joseph W., Christopher T. Middlebrook, Alexander L. Adams, Charles F. Middleton, and J. Richard Desalvo. "Tunable microwave photonic transversal filter." International Journal of Microwave and Wireless Technologies 8, no. 2 (April 16, 2015): 205–13. http://dx.doi.org/10.1017/s1759078715000215.
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We present a tapped tunable delay line filter for radiofrequency (RF) photonic filtering applications, capable of rapid tunability over a wide RF bandwidth limited only by the optical components’ losses, while maintaining independence from polarization state. Multiple fiber taps with contrasting dispersion slopes are used in intensity-modulated direct detection microwave photonic links. A temporal delay is generated between the signals within each arm of the link. Once a signal is received using balanced differential detection, nulls are generated as a function of the laser's operating wavelength. Tuning of the laser allows for a rapid shifting of the nulls in the RF spectrum to dynamically mitigate co-site interference. Through this method we demonstrate the potential for rapid tunability over the RF spectrum by the variation of the operating wavelength of the optical carrier.
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Quan, Zhiqiang, Houquan Liu, and Libo Yuan. "Simulation of On-Chip Broadband Photon Spin Router Base on Nondiffracting Surface Plasmon Beam Launching." Applied Sciences 11, no. 22 (November 11, 2021): 10643. http://dx.doi.org/10.3390/app112210643.
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The development of a photonic device based on a non-diffracting surface plasmon polariton (SPP) beam can effectively improve the anti-interference ability. Furthermore, an easily adjustable on-chip routing device is highly desirable and extremely important in practical optical communication applications. However, no non-diffracting SPP-beam-based spin routing devices with high tunability in multiple degrees of freedom have been reported. In this study, we theoretically designed a simple micro-nano structure to realize a highly adjustable non-diffracting SPP-beam-based spin router using Finite-Difference Time-Domain (FDTD) simulation. The simulation results show that the structure enables spin-controlled nondiffracting SPP-beam directional launching. The launching direction of the nondiffracting SPP beam can be dynamically rotated counterclockwise or clockwise by changing the incident angle. Hence, the routing SPP beam can be coupled to different output waveguides to provide dynamic tunability. Moreover, this device shows good broadband response ability. This work may motivate the design and fabrication of future practical photon routing devices.
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Gutiérrez, Yael, Pablo García-Fernández, Javier Junquera, April S. Brown, Fernando Moreno, and Maria Losurdo. "Polymorphic gallium for active resonance tuning in photonic nanostructures: from bulk gallium to two-dimensional (2D) gallenene." Nanophotonics 9, no. 14 (August 10, 2020): 4233–52. http://dx.doi.org/10.1515/nanoph-2020-0314.
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AbstractReconfigurable plasmonics is driving an extensive quest for active materials that can support a controllable modulation of their optical properties for dynamically tunable plasmonic structures. Here, polymorphic gallium (Ga) is demonstrated to be a very promising candidate for adaptive plasmonics and reconfigurable photonics applications. The Ga sp-metal is widely known as a liquid metal at room temperature. In addition to the many other compelling attributes of nanostructured Ga, including minimal oxidation and biocompatibility, its six phases have varying degrees of metallic character, providing a wide gamut of electrical conductivity and optical behavior tunability. Here, the dielectric function of the several Ga phases is introduced and correlated with their respective electronic structures. The key conditions for optimal optical modulation and switching for each Ga phase are evaluated. Additionally, we provide a comparison of Ga with other more common phase-change materials, showing better performance of Ga at optical frequencies. Furthermore, we first report, to the best of our knowledge, the optical properties of liquid Ga in the terahertz (THz) range showing its broad plasmonic tunability from ultraviolet to visible-infrared and down to the THz regime. Finally, we provide both computational and experimental evidence of extension of Ga polymorphism to bidimensional two-dimensional (2D) gallenene, paving the way to new bidimensional reconfigurable plasmonic platforms.
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Cao, Fengzhao, Shuai Zhang, Junhua Tong, Chao Chen, Lianze Niu, Tianrui Zhai, and Xinping Zhang. "Effects of Cavity Structure on Tuning Properties of Polymer Lasers in a Liquid Environment." Polymers 11, no. 2 (February 14, 2019): 329. http://dx.doi.org/10.3390/polym11020329.
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The effect of cavity structures on the tuning properties of polymer lasers was investigated in two common distributed-feedback cavities. The configurations of the two cavities are substrate/grating/active waveguide and substrate/active waveguide/grating, respectively. The polymer lasers were operated in the liquid environment, and the laser wavelength was tuned dynamically by changing the refractive index of the liquid. Polymer lasers based on the substrate/grating/active waveguide structure showed a higher tunability than those based on the substrate/active waveguide/grating structure due to a larger electric field distribution of the laser mode in the liquid environment. It is expected that these results will be useful in the development of tunable laser sources.
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Liu, Chengfang, He Lin, Dongzhou Ji, Qun Yu, Shuoguo Chen, Ziming Guo, Qian Luo, Xu Liu, and Wenyong Lai. "Wavelength-tunable organic semiconductor lasers based on elastic distributed feedback gratings." Journal of Semiconductors 44, no. 3 (March 1, 2023): 032601. http://dx.doi.org/10.1088/1674-4926/44/3/032601.
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Abstract Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show comparable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanical stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spectral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fabricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.
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Lin, Hai, Junling Han, and Xufeng Jing. "Electromagnetic radiation focusing lens based on phase transition all-dielectric microstructure." Journal of Laser Applications 35, no. 1 (February 2023): 012026. http://dx.doi.org/10.2351/7.0000956.
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Metasurface can adjust the polarization, amplitude, phase, polarization mode, and propagation mode of electromagnetic waves flexibly and efficiently. Based on Pancharatnam–Berry phase theory, an all-medium geometric phase element structure was proposed to construct a transmission-coded metasurface metalens. In the mid-infrared band, a phase change material (GST) is used to regulate the unit structure in order to achieve the tunability of lens focus. In order to prove that the designed hyperlens has a good focusing effect, we numerically simulate the focusing electromagnetic field distribution characteristics, and the results show that the designed geometric phase hyperlens has a good focusing effect. Using the crystal and amorphous states of phase change materials, we can dynamically control the focus of the superlens.
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Luo, Hao, Qianyi Shangguan, Yinting Yi, Shubo Cheng, Yougen Yi, and Zhizhong Li. "A Tunable “Ancient Coin”-Type Perfect Absorber with High Refractive Index Sensitivity and Good Angular Polarization Tolerance." Coatings 11, no. 7 (July 6, 2021): 814. http://dx.doi.org/10.3390/coatings11070814.
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In this paper, we design and present a graphene-based “ancient coin”-type dual-band perfect metamaterial absorber, which is composed of a silver layer, silicon dioxide layer, and a top “ancient coin” graphene layer. The absorption performance of the absorber is affected by the hollowed-out square in the center of the graphene layer and geometric parameters of the remaining nano disk. The optical properties of graphene can be changed by adjusting the voltage, to control the absorption performance of the absorber dynamically. In addition, the centrally symmetric pattern structure greatly eliminates the polarization angle dependence of our proposed absorber, and it exhibits good angular polarization tolerance. Furthermore, the proposed “ancient coin”-type absorber shows great application potential as a sensor or detector in biopharmaceutical, optical imaging, and other fields due to its strong tunability and high refractive index sensitivity.
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Gao, Liang, Chao Feng, Yongfu Li, Xiaohan Chen, Qingpu Wang, and Xian Zhao. "Actively Controllable Terahertz Metal–Graphene Metamaterial Based on Electromagnetically Induced Transparency Effect." Nanomaterials 12, no. 20 (October 19, 2022): 3672. http://dx.doi.org/10.3390/nano12203672.
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A metal–graphene metamaterial device exhibiting a tunable, electromagnetically induced transparency (EIT) spectral response at terahertz frequencies is investigated. The metamaterial structure is composed of a strip and a ring resonator, which serve as the bright and dark mode to induce the EIT effect. By employing the variable conductivity of graphene to dampen the dark resonator, the response frequency of the device shifts dynamically over 100 GHz, which satisfies the convenient post-fabrication tunability requirement. The slow-light behavior of the proposed device is also analyzed with the maximum group delay of 1.2 ps. The sensing performance is lastly studied and the sensitivity can reach up to 100 GHz/(RIU), with a figure of merit (FOM) value exceeding 4 RIU−1. Therefore, the graphene-based metamaterial provides a new miniaturized platform to facilitate the development of terahertz modulators, sensors, and slow-light applications.
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Tahmasebi, Omid, Ali Abdolali, Hamid Rajabalipanah, Ali Momeni, and Romain Fleury. "Parallel temporal signal processing enabled by polarization-multiplexed programmable THz metasurfaces." Optics Express 30, no. 25 (November 29, 2022): 45221. http://dx.doi.org/10.1364/oe.471338.
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Under the trends of multifunctionality, tunability, and compactness in modern wave-based signal processors, in this paper, we propose a polarization-multiplexed graphene-based metasurface to realize distinct mathematical operators on the parallel time-domain channels enabled by vertical and horizontal polarizations. The designed metasurface is composed of two perpendicularly-oriented graphene strips for each of which the chemical potential can be dynamically tuned through a DC biasing circuit. The programmable metasurface exhibits two orthogonal channels through which the time-domain input signals are elaborately processed by separate mathematical functions. Several illustrative examples are presented demonstrating that the proposed device can operate on different time-domain analog computing modes such as fractional-order differentiator and phaser at the same time. The strategy introduced in this paper will enable real-time parallel temporal analog computing and has potentially essential applications in terahertz spectroscopy architectures, communication systems, and computing technologies.
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Wei, Guoqiang, Qiuyue Nie, Zhonglin Zhang, Peiqi Chen, and Changshi Yan. "Plasma-based GHz tunable bandstop filter." Physics of Plasmas 29, no. 8 (August 2022): 083505. http://dx.doi.org/10.1063/5.0091487.
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Tunability is an important feature for the filter. As a special electromagnetic medium, the plasma has its permittivity being altered in a wideband range. In this work, based on the surface plasmon polaritons of plasma–dielectric–plasma waveguides, we propose a double-stubs structure submerged in a gaseous discharge plasma medium to realize tunable filtering properties in the giga-hertz (GHz) regime. The finite element method is applied to numerically compute filtering properties. The coupled mode theory and orthogonal design method are introduced to verify simulation results and estimate the effect of simulation parameters on the filtering properties. It is shown that the height of two stubs has the most important influence on filtering performance. Although once the filter is fabricated, its size cannot be modified, one can, nevertheless, vary the plasma frequency to effectively adjust the plasma frequency for the best filtering. Thus, such a plasma-modified filter provides a feasible scheme to dynamically adjust the filtering frequency.
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Wei, Xueling, Jie Nong, Yiyi Zhang, Hansi Ma, Rixing Huang, Zhenkun Yuan, Zhenfu Zhang, Zhenrong Zhang, and Junbo Yang. "Sb2S3-Based Dynamically Tuned Color Filter Array via Genetic Algorithm." Nanomaterials 13, no. 9 (April 24, 2023): 1452. http://dx.doi.org/10.3390/nano13091452.
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Color displays have become increasingly attractive, with dielectric optical nanoantennas demonstrating especially promising applications due to the high refractive index of the material, enabling devices to support geometry-dependent Mie resonance in the visible band. Although many structural color designs based on dielectric nanoantennas employ the method of artificial positive adjustment, the design cycle is too lengthy and the approach is non-intelligent. The commonly used phase change material Ge2Sb2Te5 (GST) is characterized by high absorption and a small contrast to the real part of the refractive index in the visible light band, thereby restricting its application in this range. The Sb2S3 phase change material is endowed with a wide band gap of 1.7 to 2 eV, demonstrating two orders of magnitude lower propagation loss compared to GST, when integrated onto a silicon waveguide, and exhibiting a maximum refractive index contrast close to 1 at 614 nm. Thus, Sb2S3 is a more suitable phase change material than GST for tuning visible light. In this paper, genetic algorithms and finite-difference time-domain (FDTD) solutions are combined and introduced as Sb2S3 phase change material to design nanoantennas. Structural color is generated in the reflection mode through the Mie resonance inside the structure, and the properties of Sb2S3 in different phase states are utilized to achieve tunability. Compared to traditional methods, genetic algorithms are superior-optimization algorithms that require low computational effort and a high population performance. Furthermore, Sb2S3 material can be laser-induced to switch the transitions of the crystallized and amorphous states, achieving reversible color. The large chromatic aberration ∆E modulation of 64.8, 28.1, and 44.1 was, respectively, achieved by the Sb2S3 phase transition in this paper. Moreover, based on the sensitivity of the structure to the incident angle, it can also be used in fields such as angle-sensitive detectors.
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Wang, Di, Jin Liu, Haima Yang, Bo Huang, and Guohui Zeng. "Research on Tunable SPR Sensors Based on WS2 and Graphene Hybrid Nanosheets." Photonics 9, no. 7 (July 12, 2022): 490. http://dx.doi.org/10.3390/photonics9070490.
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A prismatic excitation-based affinity biosensor consisting of the prism (BK7), WS2/graphene hybrid nanosheets, and silver (Ag) as the active metal for the surface plasmon resonance is proposed in this present research. The introduction of the transition metal WS2/graphene layer protected the silver substrate and enhanced the adsorption of biomolecules, which facilitated the quality and performance of detection. Here, we improved the detection structure by focusing on the metallic materials, graphene and WS2 film layers, and the thickness of the measured medium on the sensing effect. The results show that the silver film had a more desirable resonance effect, and the design of the symmetric detection structure produced a double resonance peak, and it provides a reference for distributed sensing. Changing the thickness of the detection medium can dynamically adjust the wave vector matching conditions, which gives the sensor a certain tunability. In the bilayer WS2 and monolayer graphene (W = 2, G = 1) configuration, the sensitivity was up to 224 deg/RIU with a quality factor of 96.97 RIU−1, which has potential for clinical analytic and biochemical detecting applications.
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Ning, Jing, Ke Chen, Wenbo Zhao, Junming Zhao, Tian Jiang, and Yijun Feng. "An Ultrathin Tunable Metamaterial Absorber for Lower Microwave Band Based on Magnetic Nanomaterial." Nanomaterials 12, no. 13 (June 21, 2022): 2135. http://dx.doi.org/10.3390/nano12132135.
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At frequencies below 1 GHz, conventional microwave absorbers are limited by their large thickness or narrow absorption bandwidth; therefore, new techniques for efficient absorption for the lower microwave band are highly demanded. Here, we propose and fabricate an ultrathin tunable metamaterial absorber combining magnetic nanomaterials and metamaterial resonant structures for use in the lower microwave band (P band). The proposed absorber utilizes electrically controlled varactors to enable frequency tunability and magnetic nanomaterials as dielectric slabs for thickness reduction and bandwidth expansion at low frequencies. By adjusting the bias voltages of varactors, the resonant behavior of the absorbing structure can be dynamically tuned that covers a continuously tunable absorbing band from 0.41 to 1.02 GHz (85.3% in fractional bandwidth) with at least 10 dB reflection reduction. The total thickness of this absorber is 5 mm, which is only about 1/146 the wavelength of the lowest frequency. The agreement between the simulated and measured results validates the proposed design, and the structure has good angular stability that may be used as complex targets for low-RCS applications.
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Yang, Guishuang, Fengping Yan, Xuemei Du, Ting Li, Wei Wang, Yuling Lv, Hong Zhou, and Yafei Hou. "Tunable broadband terahertz metamaterial absorber based on vanadium dioxide." AIP Advances 12, no. 4 (April 1, 2022): 045219. http://dx.doi.org/10.1063/5.0082295.
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The special electromagnetic properties of metamaterials have contributed to the development of terahertz technology, and terahertz broadband absorbers for various applications have been investigated. The design of metamaterial absorbers with tunability is in a particularly attractive position. In this work, a tunable broadband terahertz metamaterial absorber is proposed based on the phase transition material vanadium dioxide (VO2). The simulation results show that an excellent absorption bandwidth reaches 3.78 THz with the absorptivity over 90% under normal incidence. The absorptivity of the proposed structure can be dynamically tuned from 2.7% to 98.9% by changing the conductivity of VO2, which changes the structure from a perfect reflector to an absorber. An excellent amplitude modulation with the absorptivity is realized. The mechanism of broadband absorption is explored by analyzing the electric field distribution of the absorber based on impedance matching theory. In addition, it also has the advantage of polarization and incident angle insensitivity. The proposed absorber may have a wide range of promising applications in areas such as terahertz imaging, sensing, and detection.
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Caratenuto, Andrew, and Yi Zheng. "Piston-Type Optical Modulator for Dynamic Thermal Radiation Tuning Applications." Materials 14, no. 16 (August 4, 2021): 4372. http://dx.doi.org/10.3390/ma14164372.
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This study introduces a movable piston-like structure that provides a simple and cost-effective avenue for dynamically tuning thermal radiation. This structure leverages two materials with dissimilar optical responses—graphite and aluminum—to modulate from a state of high reflectance to a state of high absorptance. A cavity is created in the graphite to house an aluminum cylinder, which is displaced to actuate the device. In its raised state, the large aluminum surface area promotes a highly reflective response, while in its lowered state, the expanded graphite surface area and blackbody cavity-like interactions significantly enhance absorptance. By optimizing the area ratio, reflectance tunability of over 30% is achieved for nearly the entire ultraviolet, visible, and near-infrared wavelength regions. Furthermore, a theoretical analysis postulates wavelength-dependent effectivenesses as high as 0.70 for this method, indicating that tunabilities approaching 70% can be achieved by exploiting near-ideal absorbers and reflectors. The analog nature of this control method allows for an infinitely variable optical response between the upper and lower bounds of the device. These valuable characteristics would enable this material structure to serve practical applications, such as reducing cost and energy requirements for environmental temperature management operations.
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Lai, Runing, Hao Chen, Zigang Zhou, Zao Yi, Bin Tang, Jing Chen, Yougen Yi, Chaojun Tang, Jianguo Zhang, and Tangyou Sun. "Design of a Penta-Band Graphene-Based Terahertz Metamaterial Absorber with Fine Sensing Performance." Micromachines 14, no. 9 (September 21, 2023): 1802. http://dx.doi.org/10.3390/mi14091802.
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This paper presents a new theoretical proposal for a surface plasmon resonance (SPR) terahertz metamaterial absorber with five narrow absorption peaks. The overall structure comprises a sandwich stack consisting of a gold bottom layer, a silica medium, and a single-layer patterned graphene array on top. COMSOL simulation represents that the five absorption peaks under TE polarization are at fI = 1.99 THz (95.82%), fⅡ = 6.00 THz (98.47%), fⅢ = 7.37 THz (98.72%), fⅣ = 8.47 THz (99.87%), and fV = 9.38 THz (97.20%), respectively, which is almost consistent with the absorption performance under TM polarization. In contrast to noble metal absorbers, its absorption rates and resonance frequencies can be dynamically regulated by controlling the Fermi level and relaxation time of graphene. In addition, the device can maintain high absorptivity at 0~50° in TE polarization and 0~40° in TM polarization. The maximum refractive index sensitivity can reach SV = 1.75 THz/RIU, and the maximum figure of merit (FOM) can reach FOMV = 12.774 RIU−1. In conclusion, our design has the properties of dynamic tunability, polarization independence, wide-incident-angle absorption, and fine refractive index sensitivity. We believe that the device has potential applications in photodetectors, active optoelectronic devices, sensors, and other related fields.
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Chen, Fu, Yongzhi Cheng, and Hui Luo. "A Broadband Tunable Terahertz Metamaterial Absorber Based on Single-Layer Complementary Gammadion-Shaped Graphene." Materials 13, no. 4 (February 14, 2020): 860. http://dx.doi.org/10.3390/ma13040860.
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We present a simple design of a broadband tunable metamaterial absorber (MMA) in the terahertz (THz) region, which consists of a single layer complementary gammadion-shaped (CGS) graphene sheet and a polydimethylsiloxane (PDMS) dielectric substrate placed on a continuous metal film. The Fermi energy level (Ef) of the graphene can be modulated dynamically by the applied DC bias voltage, which enables us to electrically control the absorption performance of the proposed MMA flexibly. When Ef = 0.8 eV, the relative bandwidth of the proposed MMA, which represents the frequency region of absorption beyond 90%, can reaches its maximal value of 72.1%. Simulated electric field distributions reveal that the broadband absorption mainly originates from the excitation of surface plasmon polaritons (SPPs) on the CGS graphene sheet. Furthermore, the proposed MMA is polarization-insensitive and has wide angles for both transverse-electric (TE) and transverse-magnetic (TM) waves in the broadband frequency range. The broadband absorption capacity of the designed MMA can be effectively adjusted by varying the Fermi energy level of graphene. Lastly, the absorbance of the MMA can be adjusted from 42% to 99.1% by changing the Ef from 0 eV to 0.8 eV, which is in agreement with the theoretical calculation by using the interference 41theory. Due to its simple structure and flexible tunability, the proposed MMA has potential application prospects in tunable filtering, modulators, sensing, and other multispectral devices.
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Xu, Yaopengxiao, Pei-En Chen, Hechao Li, Wenxiang Xu, Yi Ren, Wanliang Shan, and Yang Jiao. "Correlation-function-based microstructure design of alloy-polymer composites for dynamic dry adhesion tuning in soft gripping." Journal of Applied Physics 131, no. 11 (March 21, 2022): 115104. http://dx.doi.org/10.1063/5.0082515.
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Tunable dry adhesion is a crucial mechanism in compliant manipulation. The gripping force can be controlled by reversibly varying the physical properties (e.g., stiffness) of the composite via external stimuli. The maximal gripping force Fmax and its tunability depend on, among other factors, the stress distribution on the gripping interface and its fracture dynamics (during detaching), which in turn are determined by the composite microstructure. Here, we present a computational framework for the modeling and design of a class of binary smart composites containing a porous low-melting-point alloy (LMPA) phase and a polymer phase, in order to achieve desirable dynamically tunable dry adhesion. We employ spatial correlation functions to quantify, model, and represent the complex bi-continuous microstructure of the composites, from which a wide spectrum of realistic virtual 3D composite microstructures can be generated using stochastic optimization. A recently developed volume-compensated lattice-particle method is then employed to model the dynamic interfacial fracture process, where the gripper is detached from the object, to compute Fmax for different composite microstructures. We focus on the interface defect tuning mechanism for dry adhesion tuning enabled by the composite, and find that for an optimal microstructure among the ones studied here, a tenfold dynamic tuning of Fmax before and after the thermal expansion of the LMPA phase can be achieved. Our computational results can provide valuable guidance for experimental fabrication of the LMPA–polymer composites.
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Wang, Bo-Yun, Zi-Hao Zhu, You-Kang Gao, Qing-Dong Zeng, Yang Liu, Jun Du, Tao Wang, and Hua-Qing Yu. "Plasmon induced transparency effect based on graphene nanoribbon waveguide side-coupled with rectangle cavities system." Acta Physica Sinica 71, no. 2 (2022): 024201. http://dx.doi.org/10.7498/aps.71.20211397.
Full textAbstract:
In order to reduce the size of the device and realize the ultrafast response time and dynamic tunableness, the single-band and dual-band plasmon induced transparency (PIT) effect are investigated based on graphene nanoribbon waveguide side-coupled rectangle cavity. The slow light properties of the model are analyzed numerically and theoretically by coupled mode theory and finite difference time domain method. With controlling the chemical potential of the graphene rectangle cavity, the tunability of the resonant wavelength and the transmission peak can be achieved simultaneously in single-band and dual-band PIT model. As the chemical potential of graphene increases, the resonant wavelength of each transmission window of PIT effect decreases gradually and presents the blue shift. In addition, through dynamically tuning the resonant wavelength of the graphene rectangle cavity, when the chemical potential of the graphene rectangle cavity increases from 0.41 to 0.44 eV, the group index of single PIT system is controlled to be between 79.2 and 28.3, and the tunable bandwidth is 477 nm. Moreover, the group index of dual PIT system is controlled to be between 143.2 and 108.6 when the chemical potentials of graphene rectangle cavities 1, 2, and 3 are 0.39–0.42 eV, 0.40–0.43 eV, and 0.41–0.44 eV, respectively. The size of the entire PIT structure is <0.5 μm<sup>2</sup>. The research results here in this work are of reference significance in designing and fabricating the optical sensors, optical filters, slow light and light storage devices with ultrafast, ultracompact and dynamic tunableness.
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Zhang, Rui, Nitin Kumar, Jennifer L. Ross, Margaret L. Gardel, and Juan J. de Pablo. "Interplay of structure, elasticity, and dynamics in actin-based nematic materials." Proceedings of the National Academy of Sciences 115, no. 2 (December 28, 2017): E124—E133. http://dx.doi.org/10.1073/pnas.1713832115.
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Achieving control and tunability of lyotropic materials has been a long-standing goal of liquid crystal research. Here we show that the elasticity of a liquid crystal system consisting of a dense suspension of semiflexible biopolymers can be manipulated over a relatively wide range of elastic moduli. Specifically, thin films of actin filaments are assembled at an oil–water interface. At sufficiently high concentrations, one observes the formation of a nematic phase riddled with ±1/2 topological defects, characteristic of a two-dimensional nematic system. As the average filament length increases, the defect morphology transitions from a U shape into a V shape, indicating the relative increase of the material’s bend over splay modulus. Furthermore, through the sparse addition of rigid microtubule filaments, one can gain additional control over the liquid crystal’s elasticity. We show how the material’s bend constant can be raised linearly as a function of microtubule filament density, and present a simple means to extract absolute values of the elastic moduli from purely optical observations. Finally, we demonstrate that it is possible to predict not only the static structure of the material, including its topological defects, but also the evolution of the system into dynamically arrested states. Despite the nonequilibrium nature of the system, our continuum model, which couples structure and hydrodynamics, is able to capture the annihilation and movement of defects over long time scales. Thus, we have experimentally realized a lyotropic liquid crystal system that can be truly engineered, with tunable mechanical properties, and a theoretical framework to capture its structure, mechanics, and dynamics.
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Gollapalli, Ravi, Jonathan Phillips, and Puneet Paul. "Ultrasensitive Surface Plasmon Resonance Sensor with a Feature of Dynamically Tunable Sensitivity and High Figure of Merit for Cancer Detection." Sensors 23, no. 12 (June 14, 2023): 5590. http://dx.doi.org/10.3390/s23125590.
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Cancer is one of the leading causes of death worldwide, and it is well known that an early detection of cancer in a human body will provide an opportunity to cure the cancer. Early detection of cancer depends on the sensitivity of the measuring device and method, where the lowest detectable concentration of the cancerous cell in a test sample becomes a matter of high importance. Recently, Surface Plasmon Resonance (SPR) has proven to be a promising method to detect cancerous cells. The SPR method is based on the detection of changes in refractive indices of samples under testing and the sensitivity of such a SPR based sensor is related to the smallest detectable change in the refractive index of the sample. There exist many techniques where different combinations of metals, metal alloys and different configurations have been shown to lead to high sensitivities of the SPR sensors. Based on the difference in the refractive index between a normal healthy cell and a cancerous cell, recently, SPR method has been shown to be applicable to detect different types of cancers. In this work, we propose a new sensor surface configuration that comprises of gold-silver-graphene-black phosphorus to detect different cancerous cells based on the SPR method. Additionally, recently we proposed that the application of electric field across gold-graphene layers that form the SPR sensor surface can provide enhanced sensitivity than that is possible without the application of electrical bias. We utilized the same concept and numerically studied the impact of electrical bias across the gold-graphene layers combined with silver and black Phosphorus layers which forms the SPR sensor surface. Our numerical results have shown that electrical bias across the sensor surface in this new heterostructure can provide enhanced sensitivity compared to the original unbiased sensor surface. Not only that, our results have shown that as the electrical bias increases, the sensitivity increases up to a certain value and stabilizes at a still improved sensitivity value. Such dependence of sensitivity on the applied bias provides a dynamic tunability of the sensitivity and figure-of-merit (FOM) of the sensor to detect different types of cancer. In this work, we used the proposed heterostructure to detect six different types of cancers: Basal, Hela, Jurkat, PC12, MDA-MB-231, and MCF-7. Comparing our results to work published recently, we were able to achieve an enhanced sensitivity ranging from 97.2 to 1851.4 (deg/RIU) and FOM values ranging from 62.13 to 89.81 far above the values presented recently by other researchers.
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Nikolaenko, Liana, Carolyn Mulroney, Peter A. Riedell, Ian W. Flinn, Jose Carlos Cruz, Rakhee Vaidya, Koen van Besien, et al. "First in Human Study of an on/Off Switchable CAR-T Cell Platform Targeting CD19 for B Cell Malignancies (CLBR001 + SWI019)." Blood 138, Supplement 1 (November 5, 2021): 2822. http://dx.doi.org/10.1182/blood-2021-151727.
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Abstract BACKGROUND: CD19 targeted chimeric antigen receptor (CAR) T cells are a transformative treatment option for patients with relapsed, refractory B cell malignancies. Despite remarkable responses in heavily pretreated patients, challenges remain related to toxicities including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), along with relapse related to tumor antigen loss. To address these challenges, we have developed a universal "switchable" CAR-T cell platform. The therapy consists of two parts including an autologous cell product comprised of a humanized, third generation CAR-T cell (CLBR001) along with a humanized antibody "switch" (SWI019) which is dosed following CLBR001 infusion. As designed, SWI019 acts as a switch to dynamically turn "on" or "off" CLBR001 cells, allowing for controllable activity of the adoptively transferred cells. This potentially offers a safer and more versatile approach to CAR-T cell therapy. METHODS: We initiated a multicenter, open label Phase I clinical study to test the safety and tolerability of CLBR001 + SWI019 in patients with relapsed/refractory B cell malignancies (NCT04450069). Autologous CLBR001 cells are manufactured from patient-derived apheresis material at a centralized manufacturing facility. Following cyclophosphamide and fludarabine lymphodepletion, patients receive a single dose of CLBR001 cells, followed by daily infusion of SWI019 for 7 days. SWI019 is administered on a 28-day cycle for up to 6 cycles. Dose escalation of CLBR001 and SWI019 is determined in the initial cohorts by a [3+3] design followed by implementation of Bayesian adaptive design (BAYDE) decision rules. RESULTS: Three patients (2 follicular lymphoma and 1 mantle cell lymphoma) in cohort 1 (140e6 CAR+ cells + 10 ug/kg SWI019) have evaluable safety and response data as of the data cut-off. CLBR001 + SWI019 was well tolerated with no DLTs observed in cohort 1. CLBR001 cell infusion was well tolerated with no adverse events attributable to the cell product in any patients during the observation period prior to SWI019 dosage, indicating CLBR001 cells do not have activity in the absence of SWI019. Elevated serum cytokine levels and CLBR001 expansion in peripheral blood was observed only after SWI019 administration. SWI019 dosage was well tolerated with 1 case of concomitant Grade 1 CRS and Grade 2 ICANS that occurred in cycle 2. This event subsided within 24 hours of administration of dexamethasone with no recurrence of CRS observed with continued administration of a reduced dose (50%) of SWI109, providing support for the tunability of the platform. In the first cohort, 2 of 3 patients experienced a complete response by Lugano criteria. CONCLUSION: This is the first report of a switchable CAR-T cell platform in patients with B cell malignancies. CLBR001 + SWI019 is safe and well tolerated in patients with B cell malignancies with encouraging clinical activity in cohort 1 using the lowest doses of both CLBR001 and SWI019. Accrual is ongoing in dose expansion cohorts of both CLBR001 cells and SWI019 switch. Updated results will be presented at the meeting. Disclosures Nikolaenko: Pfizer: Research Funding; Rafael Pharmaceuticals: Research Funding. Riedell: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Calibr: Research Funding; Kite/Gilead: Research Funding, Speakers Bureau; Xencor: Research Funding; Tessa Therapeutics: Research Funding; MorphoSys: Research Funding. Flinn: MorphoSys: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Seagen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AbbVie: Consultancy, Other: All Consultancy and Research Funding payments made to Sarah Cannon Research Institute, Research Funding; Kite, a Gilead Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; ArQule: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Agios: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Calithera Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Great Point Partners: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Forma Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Gilead Sciences: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Incyte: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Forty Seven: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Infinity Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Karyopharm Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Curis: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Janssen: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Nurix Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Juno Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Verastem: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Trillium Therapeutics: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Triphase Research & Development Corp.: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Roche: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Takeda: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Loxo: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; IGM Biosciences: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Celgene: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Iksuda Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Constellation Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Acerta Pharma: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; TG Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Teva: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Unum Therapeutics: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Genentech: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; BeiGene: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; AstraZeneca: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Merck: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Rhizen Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Novartis: Consultancy, Other: All consultancy and research funding payments made to Sarah Cannon Research Institute, Research Funding; Pfizer: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Portola Pharmaceuticals: Other: All research funding payments made to Sarah Cannon Research Institute, Research Funding; Century Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Hutchison MediPharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Vincerx Pharma: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Sarah Cannon Research Institute: Current Employment; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Yingli Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Seagen: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Servier Pharmaceuticals: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute; Unum Therapeutics: Consultancy, Other: All consultancy payments made to Sarah Cannon Research Institute, Research Funding; Johnson & Johnson: Current holder of individual stocks in a privately-held company; Seattle Genetics: Research Funding. Trikha: Abbvie: Current Employment, Current equity holder in publicly-traded company. Young: Qihan Bio: Membership on an entity's Board of Directors or advisory committees; Shoreline Bio: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding.
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Zhou, Xingfeng, Zizhao Pan, and Fusheng Ma. "Domain wall based spin torque nano-oscillator in Z-type magnetic nanowire with perpendicular magnetic anisotropy." Journal of Applied Physics 134, no. 5 (August 1, 2023). http://dx.doi.org/10.1063/5.0160400.
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A domain wall based spin torque nano-oscillator is a potential device for microwave generation because of its tunability of frequency, operation at room temperature, and integration with complementary metal–oxide–semiconductors. Here, we proposed and numerically demonstrated a spin nano-oscillator with domain wall steady oscillation in Z-type magnetic nanowires with perpendicular magnetic anisotropy by micromagnetic simulations. We find that the dynamical behavior of domain walls at Z-junctions is highly affected by the dimension of Z-junctions and current density. Three kinds of behaviors are found, i.e., damped oscillation, steady oscillation, and collapse. The observed steady oscillation can be used as spin torque nano-oscillators with a working frequency can approach 20 GHz. Our findings could enrich the investigation of spin torque nano-oscillators at high frequencies for novel microwave emitters.
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Yaqoob, M. Z., Munir Ahamd, A. Ghaffar, F. Razzaz, S. M. Saeed, and T. M. Alanazi. "Thermally tunable electromagnetic surface waves supported by graphene loaded indium antimonide (InSb) interface." Scientific Reports 13, no. 1 (October 30, 2023). http://dx.doi.org/10.1038/s41598-023-45475-8.
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AbstractThe thermal agitation plays a vital role in tunability of optoelectronic, structural and chemical characteristics of the temperature sensitive materials. Graphene enables the THz optics, due to its unprecedent controlling characteristics over the traditional materials. The influence of temperature on the monolayer graphene is very negligible due to its low free charge carrier density, to enhance the thermal sensitivity of graphene, the graphene loaded temperature sensitive material interface has been proposed. A theoretical analysis has been carried out on temperature dependent propagation characteristics of electromagnetic surface waves supported by the graphene loaded semi-infinite indium antimonide (InSb). The InSb has been taken as temperature sensitive material. The Drude model has been used for the modeling of InSb in the THz region while the modeling of the graphene has been done by random phase approximation-based Kubo’s formulism. To realize the graphene loaded indium antimonide interface, the impedance boundary conditions (IBCs) have been employed. The numerical analysis has been conducted to analyze the influence of temperature on the characteristics of electromagnetic surface waves i.e., dispersion curve, effective mode index (Neff), penetration depth (δ), propagation length (Lp), phase speed (Vp) and field profile, propagating along the graphene loaded InSb. In all the numerical results, the temperature variation has been considered from 200 to 350 K. It has been concluded that the graphene–InSb interface provides more temperature assisted tunability to the interfacial surface modes, commonly known as surface waves, as compared to monolayer graphene. Further, the graphene parameters can play a vital role in the dynamical tuning of electromagnetic surface waves in THz to IR frequency range. The numerically computed results have potential applications in designing of thermo-optical waveguides, temperature assisted communication devices, thermo-optical sensors and near field thermal imaging platforms.
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Lindsey, Rebecca K., Nir Goldman, Laurence E. Fried, and Sorin Bastea. "Chemistry-mediated Ostwald ripening in carbon-rich C/O systems at extreme conditions." Nature Communications 13, no. 1 (March 17, 2022). http://dx.doi.org/10.1038/s41467-022-29024-x.
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AbstractThere is significant interest in establishing a capability for tailored synthesis of next-generation carbon-based nanomaterials due to their broad range of applications and high degree of tunability. High pressure (e.g., shockwave-driven) synthesis holds promise as an effective discovery method, but experimental challenges preclude elucidating the processes governing nanocarbon production from carbon-rich precursors that could otherwise guide efforts through the prohibitively expansive design space. Here we report findings from large scale atomistically-resolved simulations of carbon condensation from C/O mixtures subjected to extreme pressures and temperatures, made possible by machine-learned reactive interatomic potentials. We find that liquid nanocarbon formation follows classical growth kinetics driven by Ostwald ripening (i.e., growth of large clusters at the expense of shrinking small ones) and obeys dynamical scaling in a process mediated by carbon chemistry in the surrounding reactive fluid. The results provide direct insight into carbon condensation in a representative system and pave the way for its exploration in higher complexity organic materials. They also suggest that simulations using machine-learned interatomic potentials could eventually be employed as in-silico design tools for new nanomaterials.
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Barma, Shrabanti, Md Sakib Hasan Khan, Md Rafiqul Islam, and Md Tanvir Hasan. "Intralayer spatial carrier separation capability for visible light driven photocatalytic properties of SnGe2N4-layered nanostructure: A first-principles study." AIP Advances 13, no. 7 (July 1, 2023). http://dx.doi.org/10.1063/5.0160594.
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Recently, semiconductor photocatalysts for green hydrogen (H2) fuel require two-dimensional (2D) material with semiconducting direct bandgap and enhanced visible light absorptions. In this study, the first-principles calculation of the 2D layered nanostructure of SnGe2N4 is presented for photocatalysis applications, which has a direct bandgap of 1.73 eV/2.64 eV (Perdew–Burke–Ernzerhof/Heyd–Scuseria–Ernzerhof with generalized gradient approximation) with enhanced optical absorptions. The structure is checked to confirm the chemical formidability and dynamical steadiness by formation energy calculations and phonon dispersions. To attain the tunability of electronic and optical properties, biaxial strains, together with tensile and compressive strains, are incorporated, and it is found that compressive strain widens the bandgap, whereas tensile strain causes bandgap reduction. Biaxial strains also improve the optical absorption and the highest absorption coefficient is obtained at ∼1.47 ⨯ 105 cm−1 for 6% compressive strain, comparable to conventional perovskite materials. However, in the visible spectrum, the highest absorption coefficient is obtained for 6% tensile strain. The calculated photocatalytic band edges suggest that this material has sufficient kinetic overpotential for photo redox at compressive strains in both pH = 7 and pH = 0. In addition, the spatial carrier separation is achieved due to having a large intralayer effective potential deviation of ∼6.96 eV, as well as intralayer spatial atomic group contribution in the valance band maximum and conduction band minimum. Conclusively, the analysis in this study can be a theoretical background of this layered nanostructure as a potent photocatalyst for water splitting.
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Wen, Guo-Yu, Xing-Long Zhou, Xiao-Yu Tian, Rui Xie, Xiao-Jie Ju, Zhuang Liu, Yousef Faraj, Wei Wang, and Liang-Yin Chu. "Smart hydrogels with wide visible color tunability." NPG Asia Materials 14, no. 1 (April 1, 2022). http://dx.doi.org/10.1038/s41427-022-00379-3.
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AbstractPigmentary coloration can produce viewing angle-independent uniform colors via light absorption by chromophores. However, due to the limited diversity in the changes of the molecular configuration of chromophores to undergo color change, the existing materials cannot produce a wide range of visible colors with tunable color saturation and transmittance. Herein, we propose a novel strategy to create materials with a wide visible color range and highly tunable color saturation and transmittance. We fabricated a hydrogel with poly (acrylamide-co-dopamine acrylamide) networks swollen with Fe3+-containing glycerol/water in which the covalently crosslinked polyacrylamide backbone with pendant catechols can ensure that the hydrogel maintains a very stable shape. Hydrogels containing adjustable catechol-Fe3+ coordination bonds with flexible light-interacting configuration changes can display a wide range of visible colors based on the complementary color principle. The catechol-Fe3+ complexes can dynamically switch between noncoordinated and mono-, bis- and tris-coordinated states to harvest light energy from a specific wavelength across the whole visible spectrum. Therefore, these hydrogels can be yellow, green, blue, and red, covering the three primary colors. Moreover, color saturation and transmittance can be flexibly manipulated by simply adjusting the Fe3+ content in the hydrogel networks. The versatility of these smart hydrogels has been demonstrated through diverse applications, including optical filters for color regulation and colorimetric sensors for detecting UV light and chemical vapors. This proposed smart hydrogel provides a universal color-switchable platform for the development of multifunctional optical systems such as optical filters, sensors, and detectors.
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Bell, Douglas, Neeraj Tripathi, James Grandusky, Vibhu Jindal, and Fatemeh Shahedipour-Sandvik. "A III-nitride Layered Barrier Structure for Hyperspectral Imaging Applications." MRS Proceedings 1167 (2009). http://dx.doi.org/10.1557/proc-1167-o06-03.
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AbstractWe report on a novel photodetector structure based on III-nitride materials. A layered configuration is used to create a barrier with voltage-tunable height. The barrier is used as a filter on photoexcited holes and electrons, and could form the basis for a dynamically tunable pixel in a hyperspectral imaging array. This would eliminate the need for external gratings and filters used in conventional hyperspectral instruments; in addition, the tunability of pixels allows decrease of the array dimension by one. The III-nitride materials family is a good candidate for this device, combining large band offsets with the ability for epitaxial growth. We have demonstrated the feasibility of using III-nitride materials to fabricate layered tunnel barriers, and have demonstrated tunability of photodetection using these structures. External quantum efficiencies of > 12% have been achieved with prototype devices.
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Chaplain, G. J., A. S. Gliozzi, B. Davies, D. Urban, E. Descrovi, F. Bosia, and R. V. Craster. "Tunable topological edge modes in Su–Schrieffer–Heeger arrays." Applied Physics Letters 122, no. 22 (May 29, 2023). http://dx.doi.org/10.1063/5.0152172.
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A potential weakness of topological waveguides is that they act on a fixed narrow band of frequencies. However, by 3D printing samples from a photo-responsive polymer, we can obtain a device whose operating frequency can be fine-tuned dynamically using laser excitation. This greatly enhances existing static tunability strategies, typically based on modifying the geometry. We use a version of the classical Su–Schrieffer–Heeger model to demonstrate our approach.
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Wu, Jingjun, Feng Tang, Jun Ma, Bing Han, Cong Wei, Qingzhi Li, Jun Chen, et al. "Temperature-responded tunable metalenses based on phase transition materials." Chinese Physics B, November 24, 2021. http://dx.doi.org/10.1088/1674-1056/ac3cad.
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Abstract Once the metalenses are fabricated, the functions of most are invariable. The tunability and reconfigurability are useful and cost-saving for metalenses in realistic applications. We demonstrated this tunability here via a novel hybrid metalens with the strategic placement of an ultra-thin VO2 layer. The hybrid metalens is capable of dynamically modulating the focusing intensity of transmitted light at 1550 nm, and demonstrated a 42.28% focusing efficiency of the incident light and 70.01% modulation efficiency. The hybrid metalens’ optothermal simulations show the optothermal conversion progress of dynamic focusing, and the maximum laser density of 1.76×103 W/cm2 can be handled at an ambient temperature lower than 330 K. The hybrid metalens proposed in this work, a light-dose sensitive tunable smart metalens that can protect other instruments/systems or materials from damage, has its specific applications such as anti-satellite blinding, bio-imaging, etc.
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Sabnis, Shruthi. "Tunable Microstrip Filters for Modern Wireless Communications." International Journal of Communication Networks and Security, January 2012, 1–5. http://dx.doi.org/10.47893/ijcns.2012.1026.
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Microwave filters are essential components for a large variety of modern communication systems. Filters engage in many recreating roles in RF and microwave applications. Forthcoming technologies like wireless communications are racing with RF and microwave filters in performance, physical and cost parameters. Developing technologies in materials and fabrications are defining new paths in filter designs. Tunable filters that are able to cover a number of different frequency bands are always on demand by the progressing communications technology. In this paper, Electromagnetic Band Gap (EBG) structure is studied and the novel configurations of periodic filters on dielectric materials that dynamically change their electromagnetic properties under a DC voltage bias are obtained and analysed. A tunable filter is designed using a dielectric material which produces tuning in the filter frequency. The research is carried on a single resonance element and experimented for tunability variations. S-parameter responses are obtained and analysed for the developed model through simulations. The filter with EBG structure showed tunability replacing the Liquid Crystal (LC) dielectric material is presented.