Artículos de revistas: "Modes de galerie (WGM)"

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da Silva, Jaime, Elie R. Salameh, M. Volkan Ötügen y Dominique Fourguette. "Photonic Seismometer Based on Whispering Gallery Modes". Seismological Research Letters 93, n.º 2A (26 de enero de 2022): 753–62. http://dx.doi.org/10.1785/0220210253.

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Abstract We present the concept of an all-optical seismometer based on the principle of optical whispering gallery modes (WGMs). The proposed sensor is compact, rugged, low power, and resistant to electromagnetic interference. A cantilever configuration of a fiber-pigtailed photonic integrated circuit with a ring resonator is employed as the sensing element. The measurement approach is based on the optical excitation of the WGMs of a ring resonator using a 1313 nm tunable diode laser. A digital signal processing system analyzes the recorded WGM scans. The base acceleration is calculated from the WGM shifts caused by the deformation of the optical ring resonator. A prototype seismometer is developed, calibrated, and tested. The frequency response of the seismometer is assessed by observing the free vibration of the sensor. The preliminary results are encouraging and suggest that a WGM-based optical seismometer is feasible.

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Du, Xiao-Jing, Xu-Tao Tang, Bo Xie, Lin Ma, Ma-Long Hu, Jun He y Zhong-Jian Yang. "Turning whispering-gallery-mode responses through Fano interferences in coupled all-dielectric block-disk cavities". Optics Express 31, n.º 18 (17 de agosto de 2023): 29380. http://dx.doi.org/10.1364/oe.500562.

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Here, we theoretically demonstrate a strategy for efficiently turning whispering-gallery-mode (WGM) responses of a subwavelength dielectric disk through their near-field couplings with common low-order electromagnetic resonances of a dielectric block. Both simulations and an analytical coupled oscillator model show that the couplings are Fano interferences between dark high-quality WGMs and bright modes of the block. The responses of a WGM in the coupled system are highly dependent on the strengths and the relative phases of the block modes, the coupling strength, and the decay rate of the WGM. The WGM responses of coupled systems can exceed that of the individual disk. In addition, such a configuration will also facilitate the excitation of WGMs by a normal incident plane wave in experiments. These results could enable new applications for enhancing light-matter interactions.

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3

Kozlov, D. y V. Kotlyar. "Focusing of laser light using a dielectric cylinder carrying higher-order whispering gallery modes". Computer Optics 39, n.º 3 (2015): 324–31. http://dx.doi.org/10.18287/0134-2452-2015-39-3-324-331.

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We demonstrated that plane wave diffraction on a dielectric cylinder with resonant radius produces a broader focal spot in case of TM-polarization, and resonant radiuses of whispering gallery modes (WGM) for TM-polarized illumination are significantly greater than corresponding radiuses for TE-polarization. We also showed that high order WGM are exited in cylinders with radiuses close to extreme value conditions of Bessel functions, and that increasing WGM order not necessary leads to stronger light confinement in the focal spot.

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4

Ali, Amir R. y Mohamed A. Kamel. "Mathematical Model for Electric Field Sensor Based on Whispering Gallery Modes Using Navier’s Equation for Linear Elasticity". Mathematical Problems in Engineering 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/9649524.

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This paper presents and verifies the mathematical model of an electric field senor based on the whispering gallery mode (WGM). The sensing element is a dielectric microsphere, where the light is used to tune the optical modes of the microsphere. The light undergoes total internal reflection along the circumference of the sphere; then it experiences optical resonance. The WGM are monitored as sharp dips on the transmission spectrum. These modes are very sensitive to morphology changes of the sphere, such that, for every minute change in the sphere’s morphology, a shift in the transmission spectrum will happen and that is known as WGM shifts. Due to the electrostriction effect, the applied electric field will induce forces acting on the surface of the dielectric sphere. In turn, these forces will deform the sphere causing shifts in its WGM spectrum. The applied electric field can be obtained by calculating these shifts. Navier’s equation for linear elasticity is used to model the deformation of the sphere to find the WGM shift. The finite element numerical studies are performed to verify the introduced model and to study the behavior of the sensor at different values of microspheres’ Young’s modulus and dielectric constant. Furthermore, the sensitivity and resolution of the developed WGM electric filed sensor model will be presented in this paper.

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5

Rivera-Pérez, E., A. Díez, J. L. Cruz, E. Silvestre y M. V. Andrés. "Analysis of whispering gallery modes resonators: wave propagation and energy balance models". Suplemento de la Revista Mexicana de Física 2, n.º 1 Jan-Mar (31 de marzo de 2021): 81–86. http://dx.doi.org/10.31349/suplrevmexfis.2.1.81.

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Electromagnetic whispering gallery modes (WGM) are surface waves guided by the curvature of an interface. Microspheres, microdisks and microcylinders –as for example standard optical fibers– are high quality microresonators for the WGM. In fact, they can be regarded as compact and small ring resonators. Here, we present a comparison between wave propagation and energy balance models, stablishing the equivalence and discussing the basic characteristics of these two complementary approaches.

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Zadorin, A. S. y A. A. Lukina. "A RESONANCE SYSTEM OF AN OPTOELECTRONIC OSCILLATOR BASED ON A TRANSMISSIONTYPE PLANAR OPTICAL DISK MICROCAVITY". Computer Optics 42, n.º 1 (30 de marzo de 2018): 60–66. http://dx.doi.org/10.18287/2412-6179-2018-42-1-60-66.

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It is noted that the best technical characteristics of optoelectronic microwave self-oscillators (OESO) are reached in schemes employing high-Q optical microresonators (OMR) working in the traveling wave modes (TWM). A possibility of using disk OMRs excited by fundamental whispering gallery modes (WGM) has been considered. Multielement coupling devices (CD) for such resonators have been investigated. They are constructed on the basis of planar optical waveguides (POWG) located over the disk resonator surface in a region bounded by the outer and inner caustics of the WGM. Models of this device have been proposed. The corresponding calculations have been provided.

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7

Yang, Chengkun, Hao Zhang, Bo Liu, Haifeng Liu, Chao Wang y Shiwei Lin. "Electrically tuned whispering gallery modes microresonator based on microstructured optical fibers infiltrated with dual-frequency liquid crystals". Nanophotonics 7, n.º 7 (23 de junio de 2018): 1333–40. http://dx.doi.org/10.1515/nanoph-2018-0042.

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AbstractAn electrically tunable whispering gallery mode (WGM) microresonator based on an HF-etched microstructured optical fiber (MOF) infiltrated with dual-frequency liquid crystals (DFLCs) is proposed and experimentally demonstrated for the investigation of the crossover frequency and Freedericksz transition of DFLCs. Experimental results indicate that for applied electric field with operation frequency below the crossover frequency, WGM resonance wavelength decreases with the increment of applied electric field strength. On the contrary, for applied electric field with operation frequency beyond the crossover frequency, WGM resonance dips show red shift as the applied electric field intensity increases. The proposed electrically tunable microcavity integrated with DFLCs is anticipated to find potential applications in optical filtering, all-optical switching, and electrically manipulated bi-directional micro-optics devices.

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8

Woska, Simon, Lukas Rebholz, Pascal Rietz y Heinz Kalt. "Intrinsic mode coupling in mirror-symmetric whispering gallery resonators". Optics Express 30, n.º 18 (24 de agosto de 2022): 32847. http://dx.doi.org/10.1364/oe.459348.

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Rotationally symmetric micro-cavities with disk, ring or toroidal shape displaying whispering gallery modes (WGMs) play an essential role in modern-day photonics. Due to the reduced symmetry of such resonators compared to spheres, an exact analytical model yielding WGMs as solutions does not exist. The established WGM classification scheme based on approximated analytical solutions is generally useful but neglects a possible interaction between the different modes. In this paper, we assess the limitation of the validity of this established classification based on extensive finite element method (FEM) simulations. We investigate respective mode couplings as well as underlying selection rules based on avoided crossings of the modes’ resonance wavelengths. We propose conserved mode properties solely based on true symmetries of the underlying refractive-index distribution and deduce a novel WGM classification scheme.

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9

Peng, Bo, Şahin Kaya Özdemir, Matthias Liertzer, Weijian Chen, Johannes Kramer, Huzeyfe Yılmaz, Jan Wiersig, Stefan Rotter y Lan Yang. "Chiral modes and directional lasing at exceptional points". Proceedings of the National Academy of Sciences 113, n.º 25 (6 de junio de 2016): 6845–50. http://dx.doi.org/10.1073/pnas.1603318113.

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Controlling the emission and the flow of light in micro- and nanostructures is crucial for on-chip information processing. Here we show how to impose a strong chirality and a switchable direction of light propagation in an optical system by steering it to an exceptional point (EP)—a degeneracy universally occurring in all open physical systems when two eigenvalues and the corresponding eigenstates coalesce. In our experiments with a fiber-coupled whispering-gallery-mode (WGM) resonator, we dynamically control the chirality of resonator modes and the emission direction of a WGM microlaser in the vicinity of an EP: Away from the EPs, the resonator modes are nonchiral and laser emission is bidirectional. As the system approaches an EP, the modes become chiral and allow unidirectional emission such that by transiting from one EP to another one the direction of emission can be completely reversed. Our results exemplify a very counterintuitive feature of non-Hermitian physics that paves the way to chiral photonics on a chip.

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10

Ivanov, Alexey, Kirill Min`kov, Alexey Samoilenko y Gennady Levin. "The Measurement of Nanoparticle Concentrations by the Method of Microcavity Mode Broadening Rate". Sensors 20, n.º 20 (21 de octubre de 2020): 5950. http://dx.doi.org/10.3390/s20205950.

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A measurement system for the detection of a low concentration of nanoparticles based on optical microcavities with whispering-gallery modes (WGMs) is developed and investigated. A novel method based on the WGM broadening allows us to increase the precision of concentration measurements up to 0.005 ppm for nanoparticles of a known size. We describe WGM microcavity manufacturing and quality control methods. The collective interaction process of suspended Ag nanoparticles in a liquid and TiO2 in the air with a microcavity surface is studied.

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11

Oki, Osamu, Soh Kushida, Annabel Mikosch, Kota Hatanaka, Youhei Takeda, Satoshi Minakata, Junpei Kuwabara et al. "FRET-mediated near infrared whispering gallery modes: studies on the relevance of intracavity energy transfer with Q-factors". Materials Chemistry Frontiers 2, n.º 2 (2018): 270–74. http://dx.doi.org/10.1039/c7qm00498b.

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12

Okada, Naoki, James B. Cole, Shigeki Yamada, Kensuke Ogawa y Yoshifumi Katayama. "Nonstandard FDTD Simulation-Based Design of CROW Wavelength Splitters". Advances in Optical Technologies 2011 (1 de junio de 2011): 1–6. http://dx.doi.org/10.1155/2011/265702.

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The finite-difference time-domain (FDTD) algorithm has been used in simulation-based designs of many optical devices, but it fails to reproduce high-Q whispering gallery modes (WGMs). On the other hand, the nonstandard (NS) FDTD algorithm can accurately compute WGMs and can be used to make simulation-based designs of WGM devices. Wavelength splitters using the coupled resonator optical waveguides (CROWs) based on WGM couplings have recently attracted attention because they are potentially ultracompact. In this paper, we design a CROW wavelength splitter using NS FDTD simulations and demonstrate high interchannel extinction ratios of over 20 dB.

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13

Yang, Han y Yue-Gang Chen. "Subnanometer-Resolution Nanoparticle Sensing through the Strong Coupling between Surface Plasmon Polariton Whispering Gallery Resonances and Localized Surface Plasmon". Photonics 10, n.º 2 (15 de febrero de 2023): 212. http://dx.doi.org/10.3390/photonics10020212.

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High-resolution nanoparticle sensing is very important, and many schemes have been proposed to achieve this goal. Circular nanocavities in which surface plasmon polariton (SPP) whispering gallery mode (WGM) resonances were excited were designed to sense particles of ultra-small size and with high resolution. Localized surface plasmon resonances (LSPRs) were excited when a metal particle was set in the circular cavity. The SPP WGM split into symmetric mode (SM) and antisymmetric mode (ASM) due to the LSPRs scattering into the SPPs. The strong coupling between SM resonance and LSPRs generated positive and opposite modes, which were sensitive to the variation in nanoparticle size and position. Even a small nanometer-sized metal particle introduced LSPRs and produced mode splitting. The WGM mode splitting induced by LSPRs reduced the sensing limit. The simulation results show that 1 nm changes in nanoparticle radius and position led to SM 11.8 nm and 10.2 nm wavelength shifts, respectively. This means that variations of 0.09 nm in size and 0.1 nm in position can be sensed with a 1 nm spectral resolution. The strong coupling between SPP WGM and LSPRs can be applied to sense at a subnanometer resolution.

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14

Wang, Xingyuan, Xiaoyong Hu y Tianrui Zhai. "Vortex Laser Based on a Plasmonic Ring Cavity". Crystals 11, n.º 8 (31 de julio de 2021): 901. http://dx.doi.org/10.3390/cryst11080901.

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The orbital angular momentum (OAM) of the structure light is viewed as a candidate for enhancing the capacity of information processing. Microring has advantages in realizing the compact lasers required for on-chip applications. However, as the clockwise and counterclockwise whispering gallery modes (WGM) appear simultaneously, the emitted light from the normal microring does not possess net OAM. Here, we propose an OAM laser based on the standing-wave WGMs containing clockwise and counterclockwise WGM components. Due to the inhomogeneous intensity distribution of the standing-wave WGM, the single-mode lasing for the OAM light can be realized. Besides, the OAM of the emitted light can be designed on demand. The principle and properties of the proposed laser are demonstrated by numerical simulations. This work paves the way for exploring a single-mode OAM laser based on the plasmonic standing-wave WGMs at the microscale, which can be served as a basic building block for on-chip optical devices.

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Niu, Ben, Kun Ge, Zhiyang Xu, Xiaoyu Shi, Dan Guo y Tianrui Zhai. "Laser Diode Pumped Polymer Lasers with Tunable Emission Based on Microfluidic Channels". Polymers 13, n.º 20 (13 de octubre de 2021): 3511. http://dx.doi.org/10.3390/polym13203511.

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Tunable whispering-gallery-mode (WGM) lasers have been paid lots of attention for their potential applications in the photonic field. Here, a tunable polymer WGM laser based on laser diode pumping is realized with a threshold of 0.43 MW/cm2 per pulse. The WGM laser is realized by a microfluidic microcavity, which consists of a quartz capillary and gain materials. The laser performance keeps stable for a long time (3.5 h), pumped by a 50-ns 50 Hz laser diode with a pumping peak power density of 1.08 MW/cm2 per pulse. The lasing wavelength can be tuned over 15 nm by changing the gain material concentration from 3.5 mg/mL to 12.5 mg/mL in the microfluidic channel. Moreover, the lasing mode can be switched between transverse magnetic (TM) and transverse electric (TE) modes by adjusting the pump polarization. These results provide the basis for designing nanophotonic devices with laser diode pumping.

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Zhang, Ping, Dongyue He, Chen Zhang y Zhiruo Yan. "FDTD Simulation: Simultaneous Measurement of the Refractive Index and the Pressure Using Microdisk Resonator with Two Whispering-Gallery Modes". Sensors 20, n.º 14 (16 de julio de 2020): 3955. http://dx.doi.org/10.3390/s20143955.

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In this paper, an approach to measure both the refractive index (RI) and the pressure simultaneously using two Whispering-Gallery Modes (WGMs) in a microdisk resonator is theoretically proposed. Due to the difference in the energy distribution of the first and second order WGMs, the sensitivity of two modes toward the variation of RI and pressure applied to the device show differences. An RI sensitivity of 29.07 nm/RIU and pressure sensitivity of 0.576 pm/kPa for WGM (1,36), and an RI sensitivity of 38.68 nm/RIU and a pressure sensitivity of 0.589 pm/kPa for WGM (2,28) are obtained through the 3D finite-difference time-domain (3D-FDTD) simulation. Dual parametric sensing can be achieved by solving the second-order inverse sensitivity matrix. Therefore, strain–optical coupling behavior is effectively eliminated. The dual sensing scheme we proposed provides a novel approach to overcome the difficulty of multi-sensing applications based on the flexible photonic device.

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17

Ge, Kun, Ben Niu, Fangyuan Liu, Jun Ruan, Zhiyang Xu, Dan Guo, Xiaolei Wang, Linzheng Lv y Tianrui Zhai. "Electrically tunable WGM lasing in a metal-dielectric core–shell hybrid microcavity". Applied Physics Letters 120, n.º 23 (6 de junio de 2022): 232201. http://dx.doi.org/10.1063/5.0096732.

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We present a hybrid cavity designed to manipulate lasing modes, consisting of a metal-dielectric core–shell hybrid microcavity fabricated using a simple brush-coating method. Single and multiple modes can be obtained in the proposed laser device by the trade-off between loss and gain. Moreover, we achieve electrically tunable whispering-gallery-mode lasing by employing the thermo-optic effect in the hybrid microcavity. The lasing peak of the modes can be electrically tuned by quantitative control of Joule heating. We measure a tuning rate of 15.3 pm/J for all the lasing peaks.

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Chang, Pengfa, Chen Wang, Hong Han, Feng Gao, Ligang Huang y Anbang Wang. "Tunable Narrow-Linewidth Ring Laser Based on the Polarization Conversion in a Tapered Fiber-Coupled Whispering Gallery Mode Resonator". Crystals 11, n.º 11 (23 de octubre de 2021): 1285. http://dx.doi.org/10.3390/cryst11111285.

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Based on the polarization conversion in a tapered fiber-coupled whispering gallery mode (WGM) system, a simple-structured narrow linewidth band-pass filter was fabricated and a narrow linewidth ring laser was demonstrated. With a fiber Bragg grating (FBG) to further select the resonant mode, the ring laser could be in the single-longitudinal-mode with the linewidth about 6 kHz and its wavelength could be tuned from 1540.10 nm to 1570.01 nm. Benefit from the dense modes in the WGM resonator, high conversion efficiency, and better stability of the structure, a tunable dual-wavelength laser could be achieved based on two FBGs with different resonant wavelengths. The configuration of the proposed laser is simple and stable, which will benefit its applications in the future.

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Dukin A. A. y Golubev V. G. "Modeling of luminescence spectra in spherical microresonators with an emitting shell". Optics and Spectroscopy 130, n.º 13 (2022): 2033. http://dx.doi.org/10.21883/eos.2022.13.53986.2266-21.

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The luminescence spectra of a microresonator structure consisting of a spherical core of small diameter (3.5-6 mcm) covered with a luminescent shell with a refractive index less than that of the core are modeled. Shell luminescence spectra, radial distribution of the whispering gallery mode (WGM) field, and mode parameters (wavelength, width, quality factor) are calculated using the expansion of the electromagnetic wave field in the basis of vector spherical harmonics and the method of spherical wave transfer matrices. The dependence of the luminescence spectra and WGM parameters on the geometric and optical parameters of the structure --- the shell thickness, the refractive index of the shell, and the core diameter --- is studied. Keywords: spherical microresonator, luminescent shell, whispering gallery modes, modeling of luminescence spectra.

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Wang, Yuchen, Hongsheng Li, Shu Hu, Heng Li y Chuanxiang Sheng. "Unusual Polarization Relation between Single-Mode Lasing Emission and Excitation Laser from an Evanescent-Wave Pumped Micro-Cavity Laser". Photonics 8, n.º 3 (26 de febrero de 2021): 66. http://dx.doi.org/10.3390/photonics8030066.

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Using a fiber of that is 125 μm in diameter in rhodamine 6G ethanol solution, controllable multi- and single-whispering-gallery-mode (WGM) optofluidic lasers based on evanescent-wave-coupled gain are both available. With multi-mode WGM emission, lasing emission with almost pure TM (transverse magnetic) or almost TE (transverse electric) modes can be obtained when the pump laser has an electric field parallel (perpendicular) to the fiber axis, i.e., the polarization direction of output laser is the same as that of the pump laser. On the other hand, when the laser emission is single-mode, the TE output laser always emerges firstly above lasing threshold, then keeps TE mode while the pump laser’s intensity increases with polarization direction perpendicular to the fiber axis; on the contrary, TE emission will dwindle relatively, while the TM emission emerges and dominates the spectra, when the pump laser’s intensity increases with polarization parallel to the fiber axis. Our work proves that controlling the leakage of the evanescent wave from high-Q microcavities is crucial for both modes of lasing emission and its polarization.

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Li, Jiaxing, Qiang Li, Ransheng Chen, Qifan Zhang, Wannian Fang, Kangkang Liu, Feng Li y Feng Yun. "Single-Mode Control and Individual Nanoparticle Detection in the Ultraviolet Region Based on Boron Nitride Microdisk with Whispering Gallery Mode". Nanomaterials 14, n.º 6 (11 de marzo de 2024): 501. http://dx.doi.org/10.3390/nano14060501.

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Optical microcavities are known for their strongly enhanced light–matter interactions. Whispering gallery mode (WGM) microresonators have important applications in nonlinear optics, single-mode output, and biosensing. However, there are few studies on resonance modes in the ultraviolet spectrum because most materials with high absorption properties are in the ultraviolet band. In this study, the performance of a microdisk cavity based on boron nitride (BN) was simulated by using the Finite-difference time-domain (FDTD) method. The WGM characteristics of a single BN microdisk with different sizes were obtained, wherein the resonance modes could be regulated from 270 nm to 350 nm; additionally, a single-mode at 301.5 nm is achieved by cascading multiple BN microdisk cavities. Moreover, we found that a BN microdisk with a diameter of 2 μm has a position-independent precise sensitivity for the nanoparticle of 140 nm. This study provides new ideas for optical microcavities to achieve single-mode management and novel coronavirus size screening, such as SARS-CoV-2, in the ultraviolet region.

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François, Alexandre, Tess Reynolds, Nicolas Riesen, Jonathan M. M. Hall, Matthew R. Henderson, Enming Zhao, Shahraam Afshar V. y Tanya M. Monro. "Combining whispering gallery mode lasers and microstructured optical fibers: limitations, applications and perspectives for in-vivo biosensing". MRS Advances 1, n.º 33 (2016): 2309–20. http://dx.doi.org/10.1557/adv.2016.342.

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ABSTRACTWhispering gallery modes (WGMs) have been widely studied over the past 20 years for various applications, including biological sensing. While the WGM-based sensing approaches reported in the literature have shown tremendous performance down to single molecule detection, at present such sensing technologies are not yet mature and still have significant practical constraints that limit their use in real-world applications. Our work has focused on developing a practical, yet effective, WGM-based sensing platform capable of being used as a dip sensor for in-vivo biosensing by combining WGM fluorescent microresonators with silica Microstructured Optical Fibers (MOFs).We recently demonstrated that a suspended core MOF with a dye-doped polymer microresonator supporting WGMs positioned onto the tip of the fiber, can be used as a dip sensor. In this architecture the resonator is anchored to one of the MOF air holes, in contact with the fiber core, enabling a significant portion of the evanescent field from the fiber to overlap with the sphere and hence excite the fluorescent WGMs. This architecture allows for remote excitation and collection of the WGMs. The fiber also permits easy manipulation of the microresonator for dip sensing applications, and hence alleviates the need for a complex microfluidic interface. More importantly, it allows for an increase in both the excitation and collection efficiency compared to free space coupling, and also improves the Q factor.In this paper we present our recent results on microstructured fiber tip WGM-based sensors and show that this sensing platform can be used in clinical diagnostics, for detecting various clinically relevant biomarkers in complex clinical samples.

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Choi, Yoo-Jin. "An Analysis of Robes of Amadeus Heroins Using Galerie des Modes". Journal of Korean Traditional Costume 27, n.º 1 (31 de marzo de 2024): 141–55. http://dx.doi.org/10.16885/jktc.2024.03.27.1.141.

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Tarasov, Andrey P., Arsen E. Muslimov y Vladimir M. Kanevsky. "Excitonic Mechanisms of Stimulated Emission in Low-Threshold ZnO Microrod Lasers with Whispering Gallery Modes". Materials 15, n.º 24 (7 de diciembre de 2022): 8723. http://dx.doi.org/10.3390/ma15248723.

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Whispering gallery mode (WGM) ZnO microlasers gain attention due to their high Q-factors and ability to provide low-threshold near-UV lasing. However, a detailed understanding of the optical gain mechanisms in such structures has not yet been achieved. In this work, we study the mechanisms of stimulated emission (SE) in hexagonal ZnO microrods, demonstrating high-performance WGM lasing with thresholds down to 10–20 kW/cm2 and Q-factors up to ~3500. The observed SE with a maximum in the range of 3.11–3.17 eV at room temperature exhibits a characteristic redshift upon increasing photoexcitation intensity, which is often attributed to direct recombination in the inverted electron-hole plasma (EHP). We show that the main contribution to room-temperature SE in the microrods studied, at least for near-threshold excitation intensities, is made by inelastic exciton-electron scattering rather than EHP. The shape and perfection of crystals play an important role in the excitation of this emission. At lower temperatures, two competing gain mechanisms take place: exciton-electron scattering and two-phonon assisted exciton recombination. The latter forms emission with a maximum in the region near ~3.17 eV at room temperature without a significant spectral shift, which was observed only from weakly faceted ZnO microcrystals in this study.

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Kang, Yvonne, Alexandre François, Nicolas Riesen y Tanya Monro. "Mode-Splitting for Refractive Index Sensing in Fluorescent Whispering Gallery Mode Microspheres with Broken Symmetry". Sensors 18, n.º 9 (7 de septiembre de 2018): 2987. http://dx.doi.org/10.3390/s18092987.

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Whispering gallery mode (WGM) resonators have become increasingly diverse in terms of both architecture and applications, especially as refractometric sensors, allowing for unprecedented levels of sensitivity. However, like every refractometric sensor, a single WGM resonator cannot distinguish temperature variations from changes in the refractive index of the surrounding environment. Here, we investigate how breaking the symmetry of an otherwise perfect fluorescent microsphere, by covering half of the resonator with a high-refractive-index (RI) glue, might enable discrimination of changes in temperature from variations in the surrounding refractive index. This novel approach takes advantage of the difference of optical pathway experienced by WGMs circulating in different equatorial planes of a single microsphere resonator, which induces mode-splitting. We investigated the influence of the surrounding RI of the microsphere on mode-splitting through an evaluation of the sphere’s WGM spectrum and quality factor (Q-factor). Our results reveal that the magnitude of the mode-splitting increases as the refractive index contrast between the high-refractive-index (RI) glue and the surrounding environment increases, and that when they are equal no mode-splitting can be seen. Investigating the refractive index sensitivity of the individual sub modes resulting from the mode-splitting unveils a new methodology for RI sensing, and enables discrimination between surrounding refractive index changes and temperature changes, although it comes at the cost of an overall reduced refractive index sensitivity.

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Anashkina, Elena A., Maria P. Marisova y Alexey V. Andrianov. "Theoretical Study of Multicascade Raman Microlasers Based on TeO2–WO3–Bi2O3 Glass". Photonics 10, n.º 10 (11 de octubre de 2023): 1137. http://dx.doi.org/10.3390/photonics10101137.

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The development and investigation of miniature narrow-line coherent light sources based on microresonators with low-power-consumption whispering gallery modes (WGMs) is an actual trend in modern photonics. Raman WGM microlasers can operate at wavelengths inaccessible to traditional laser media and provide a huge pump frequency tuning range. Here, we propose and theoretically study multicascade Raman microlasers based on soft tellurite TeO2–WO3–Bi2O3 glass WGM microresonators (microspheres) which can operate in the near-IR and mid-IR with the pump in the telecommunication range. Thanks to a large Raman gain (120 times exceeding the maximum Raman gain of silica glass) and a huge Raman frequency shift of 27.5 THz for this glass, the Raman waves at 1.83 µm, 2.21 µm, 2.77 µm, and 3.7 µm in the first, second, third, and fourth cascades, respectively, are theoretically demonstrated with a pump at 1.57 µm. We analyze in detail the influence of different factors on the characteristics of the generated Raman waves, such as microsphere diameters, Q-factors, pump powers, and detuning of the pump frequency from exact resonance. We also solve a thermo-optical problem to show that the temperature of a soft glass microresonator heated due to partial thermalization of pump power remains below the glass transition temperature. To the best of our knowledge, mid-IR tellurite glass Raman WGM microlasers have not been studied before.

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Chiavaioli, Francesco, Dario Laneve, Daniele Farnesi, Mario Falconi, Gualtiero Nunzi Conti, Francesco Baldini y Francesco Prudenzano. "Long Period Grating-Based Fiber Coupling to WGM Microresonators". Micromachines 9, n.º 7 (23 de julio de 2018): 366. http://dx.doi.org/10.3390/mi9070366.

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A comprehensive model for designing robust all-in-fiber microresonator-based optical sensing setups is illustrated. The investigated all-in-fiber setups allow light to selectively excite high-Q whispering gallery modes (WGMs) into optical microresonators, thanks to a pair of identical long period gratings (LPGs) written in the same optical fiber. Microspheres and microbubbles are used as microresonators and evanescently side-coupled to a thick fiber taper, with a waist diameter of about 18 µm, in between the two LPGs. The model is validated by comparing the simulated results with the experimental data. A good agreement between the simulated and experimental results is obtained. The model is general and by exploiting the refractive index and/or absorption characteristics at suitable wavelengths, the sensing of several substances or pollutants can be predicted.

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Mintairov, A. M., J. L. Merz, J. Kapaldo, A. S. Vlasov y S. A. Blundell. "Wigner localization and whispering gallery modes of electrons in quantum dots". Физика и техника полупроводников 52, n.º 4 (2018): 478. http://dx.doi.org/10.21883/ftp.2018.04.45827.16.

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AbstractWe used a low temperature near-field scanning optical microscopy (NSOM) to study a formation of Wigner molecules (WMs) in the emission spectra of self-organized InP/GaInP QDs having up to seven electrons. We used a Schottky diode structure for the electrostatic control of the number of the electrons ( N ) in QD, and we observed the emission of the charged excitons (for N < 3) and of the WMs (for N > 2) in the regime of weak Wigner localization. We show, that a contribution of whispering gallery modes (WGMs) of the electrons and rearrangement of the electrons between the WM and WGM states in the QDs, can explain the anomalous dependence of NSOM image size on the quantum confinement observed for some dots.

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29

Jorge, Gabriel H. A., Filipe A. Couto, Juliana M. P. Almeida, Victor A. S. Marques, Marcelo B. Andrade y Cleber R. Mendonça. "Active Optical Tuning of Azopolymeric Whispering Gallery Mode Microresonators for Filter Applications". Photonics 11, n.º 2 (9 de febrero de 2024): 167. http://dx.doi.org/10.3390/photonics11020167.

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Light confinement provided by whispering gallery mode (WGM) microresonators is especially useful for integrated photonic circuits. In particular, the tunability of such devices has gained increased attention for active filtering and lasering applications. Traditional lithographic approaches for fabricating such devices, especially Si-based ones, often restrict the device’s tuning due to the material’s inherent properties. Two-photon polymerization (2PP) has emerged as an alternative fabrication technique of sub-diffraction resolution 3D structures, in which compounds can be incorporated to further expand their applications, such as enabling active devices. Here, we exploited the advantageous characteristics of polymer-based devices and produced, via 2PP, acrylic-based WGM hollow microcylinders incorporated with the azoaromatic chromophore Disperse Red 13 (DR13). Within telecommunication range, we demonstrated the tuning of the microresonator’s modes by external irradiation within the dye’s absorption peak (at 514 nm), actively inducing a blueshift at a rate of 1.2 nm/(Wcm−2). Its thermo-optical properties were also investigated through direct heating, and the compatibility of both natural phenomena was also confirmed by finite element simulations. Such results further expand the applicability of polymeric microresonators in optical and photonic devices since optically active filtering was exhibited.

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30

Wang, Zhe, Arun Kumar Mallik, Fangfang Wei, Zhuochen Wang, Anuradha Rout, Qiang Wu y Yuliya Semenova. "A Micron-Range Displacement Sensor Based on Thermo-Optically Tuned Whispering Gallery Modes in a Microcapillary Resonator". Sensors 22, n.º 21 (29 de octubre de 2022): 8312. http://dx.doi.org/10.3390/s22218312.

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A novel micron-range displacement sensor based on a whispering-gallery mode (WGM) microcapillary resonator filled with a nematic liquid crystal (LC) and a magnetic nanoparticle- coated fiber half-taper is proposed and experimentally demonstrated. In the proposed device, the tip of a fiber half-taper coated with a thin layer of magnetic nanoparticles (MNPs) moves inside the LC-filled microcapillary resonator along its axis. The input end of the fiber half-taper is connected to a pump laser source and due to the thermo-optic effect within the MNPs, the fiber tip acts as point heat source increasing the temperature of the LC material in its vicinity. An increase in the LC temperature leads to a decrease in its effective refractive index, which in turn causes spectral shift of the WGM resonances monitored in the transmission spectrum of the coupling fiber. The spectral shift of the WGMs is proportional to the displacement of the MNP-coated tip with respect to the microcapillary’s light coupling point. The sensor’s operation is simulated considering heat transfer in the microcapillary filled with a LC material having a negative thermo-optic coefficient. The simulations are in a good agreement with the WGMs spectral shift observed experimentally. A sensitivity to displacement of 15.44 pm/µm and a response time of 260 ms were demonstrated for the proposed sensor. The device also shows good reversibility and repeatability of response. The proposed micro-displacement sensor has potential applications in micro-manufacturing, precision measurement and medical instruments.

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31

Chen, Zeji, Qianqian Jia, Wenli Liu, Quan Yuan, Yinfang Zhu, Jinling Yang y Fuhua Yang. "Dominant Loss Mechanisms of Whispering Gallery Mode RF-MEMS Resonators with Wide Frequency Coverage". Sensors 20, n.º 24 (8 de diciembre de 2020): 7017. http://dx.doi.org/10.3390/s20247017.

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This work investigates the dominant energy dissipations of the multi-frequency whispering gallery mode (WGM) resonators to provide an insight into the loss mechanisms of the devices. An extensive theory for each loss source was established and experimentally testified. The squeezed film damping (SFD) is a major loss for all the WGMs at atmosphere, which is distinguished from traditional bulk acoustic wave (BAW) resonators where the high-order modes suffer less from the air damping. In vacuum, the SFD is negligible, and the frequency-dependent Akhiezer damping (AKE) has significant effects on different order modes. For low-order WGMs, the AKE is limited, and the anchor loss behaves as the dominant loss. For high-order modes with an extended nodal region, the anchor loss is reduced, and the AKE determines the Q values. Substantial Q enhancements over four times and an excellent f × Q product up to 6.36 × 1013 at 7 K were achieved.

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32

Dukin A. A. y Golubev V. G. "Features of the shape of the emission spectrum of a spherical microresonator with a high refractive index luminescent shell due to the polarization of the whispering gallery modes". Optics and Spectroscopy 130, n.º 11 (2022): 1465. http://dx.doi.org/10.21883/eos.2022.11.55107.3857-22.

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The effect of the thickness and refractive index of the shell on the amplitudes of lines of the TE and TM polarized whispering gallery modes (WGMs) in the emission spectrum of a microcavity structure consisting of a spherical core covered with a luminescent shell with a refractive index greater than that of the core is studied. The luminescence spectra of the shell, the radial distribution of the WGM field, and the mode parameters (wavelength, quality factor, and effective volume) are calculated using the method of spherical wave transfer matrices. It is shown that at certain subwavelength shell thicknesses, the amplitude of the TE mode emission peak is many times greater than the amplitude of the TM mode peak with the same polar, azimuthal, and radial indices. This is explained by the fact that with these parameters of the shell, WGMs propagate inside the shell as waveguide modes. Keywords: spherical microresonator, high refractive index luminescent shell, whispering gallery modes, mode polarization, amplitude of emission lines.

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33

Adnan Zain, Huda, Malathy Batumalay, Hazlihan Haris, Ismail Saad, Ahmad Razif Muhammad, Siti Nasuha Mustaffa, Arni Munira Markom, Hazli Rafis Abdul Rahim, Sin Jin Tan y Sulaiman Wadi Harun. "Review of Microbottle Resonators for Sensing Applications". Micromachines 14, n.º 4 (26 de marzo de 2023): 734. http://dx.doi.org/10.3390/mi14040734.

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Microbottle resonators (MBR) are bottle-like structures fabricated by varying the radius of an optical fiber. MBRs can support whispering gallery modes (WGM) by the total internal reflection of the light coupled into the MBRs. MBRs have a significant advantage in sensing and other advanced optical applications due to their light confinement abilities in a relatively small mode volume and having high Q factors. This review starts with an introduction to MBRs’ optical properties, coupling methods, and sensing mechanisms. The sensing principle and sensing parameters of MBRs are discussed here as well. Then, practical MBRs fabrication methods and sensing applications are presented.

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34

Yakuhina, Anastasia, Alexey Kadochkin, Vladimir Amelichev, Dmitry Gorelov y Sergey Generalov. "Research of Constructive and Technological Methods for Forming a Silicon Disk Resonator with Whispering Gallery Modes". Photonics 7, n.º 2 (22 de abril de 2020): 31. http://dx.doi.org/10.3390/photonics7020031.

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This article presents the results of a computer simulation of whispering gallery modes in the structure of a silicon disk resonator with a wedge-shaped profile made on a silicon-on-isolator base (SOI). The rationale for the choice of silicon as a material for its manufacturing is given. The results of the study of the influence of the wedge angle on the whispering gallery mode parameters (WGM) are presented. The optimum wedge angle of a silicon disk resonator is determined, which ensures the minimum loss and maximum mode stability. The technological aspects of plasma-chemical etching processes for forming a wedge-shaped profile of the edge of a silicon disk resonator are studied.

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35

Дукин, А. А. y В. Г. Голубев. "Особенности формы спектра излучения сферического микрорезонатора с люминесцентной оболочкой с высоким показателем преломления, обусловленные поляризацией мод шепчущей галереи". Оптика и спектроскопия 130, n.º 11 (2022): 1731. http://dx.doi.org/10.21883/os.2022.11.53781.3857-22.

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The effect of the thickness and refractive index of the shell on the amplitudes of lines of the TE and TM polarized whispering gallery modes (WGMs) in the emission spectrum of a microcavity structure consisting of a spherical core covered with a luminescent shell with a refractive index greater than that of the core is studied. The luminescence spectra of the shell, the radial distribution of the WGM field, and the mode parameters (wavelength, quality factor, and effective volume) are calculated using the method of spherical wave transfer matrices. It is shown that at certain subwavelength shell thicknesses, the amplitude of the TE mode emission peak is many times greater than the amplitude of the TM mode peak with the same polar, azimuthal, and radial indices. This is explained by the fact that with these parameters of the shell, WGMs propagate inside the shell as waveguide modes.

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36

Michihata, Masaki, Akifumi Kawasaki y Yasuhiro Takaya. "Precise Diameter Measurement of a Microsphere Based on Polarization Analysis of Whispering Gallery Mode Resonance". Applied Mechanics and Materials 870 (septiembre de 2017): 108–13. http://dx.doi.org/10.4028/www.scientific.net/amm.870.108.

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Whispering gallery mode (WGM) resonance is used for the diameter measuring method of a microsphere smaller than φ 1 mm. It is aimed to achieve measurement accuracy better than 10 nm. There are two electromagnetic modes for WGMs, and then mis-detection of the electromagnetic mode expands measurement errors more than 100 nm, so it is indispensably to distinguish the electromagnetic mode. As theoretical simulation implies, polarization mode of WGMs can be selectively excited by controlling polarization of the incident light in optical coupling. Based on the analysis, it was proofed experimentally that the polarization of WGMs could be classified. As a result, the diameter measurement for a microsphere was performed with measurement error of ± 1 nm.

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37

Chen, Jian, Yongchao Dong, Han Wang, Penghui Sun y Xueliang Zeng. "Simulation and Optimization of SNAP-Taper Coupling System in Displacement Sensing". Sensors 21, n.º 9 (22 de abril de 2021): 2947. http://dx.doi.org/10.3390/s21092947.

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Sensing applications based on whispering gallery mode (WGM) microcavities have attracted extensive attention recently, especially in displacement sensing applications. However, the traditional displacement sensing scheme based on shift in a single resonance wavelength, has a lot of drawbacks. Herein, a novel displacement sensing scheme based on the surface nanoscale axial photonics (SNAP) is proposed to achieve a wide range and high-resolution displacement sensor through analyzing the transmittance of multiple axial modes. By analyzing the surface plot of the resonance spectrum with different coupling positions, the ideal coupling parameters and ERV for displacement sensing are obtained. In the following, displacement sensing with high sensitivity and a wide range is theoretically realized through adjusting the sensitivity threshold and the number of modes. Finally, we present our views on the current challenges and the future development of the displacement sensing based on an SNAP resonator. We believe that a comprehensive understanding on this sensing scheme would significantly contribute to the advancement of the SNAP resonator for a broad range of applications.

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38

Zadorozhnaya, Ludmila A., Andrey P. Tarasov y Vladimir M. Kanevsky. "The Growth Mechanism, Luminescence, and Lasing of Polyhedral ZnO Microcrystals with Whispering-Gallery Modes". Photonics 10, n.º 12 (29 de noviembre de 2023): 1328. http://dx.doi.org/10.3390/photonics10121328.

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This work studies the features of the formation of isometric polyhedral ZnO microcrystals that provide stimulated emission and whispering-gallery-mode (WGM) lasing in the near-UV range. For this purpose, the growth stages of such crystals in the process of gas-transport synthesis and the luminescent properties of the structures obtained at each stage were investigated. It was shown that the growth of laser microcrystals begins with the formation of microspheroids with thin ZnO shells. Such spheroids exhibit mainly white luminescence with a small contribution of near-UV emission. Increasing the synthesis duration results in thickening and faceting of the spheroid shells, as well as a decrease in the contribution of the yellow–red component to the luminescence spectrum. At the same time, ZnO microcrystallites nucleate and grow inside the spheroids, using as a material the remains of a liquid zinc drop and oxygen entering the spheroids through their shells. Such growth conditions allow them to take on an equilibrium polyhedral shape. Eventually, upon destruction of the spheroid shell, a polyhedral ZnO microcrystal supporting WGMs is observed.

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39

Xu, H., Z. Cai, G. Stéphan, P. Féron y M. Mortier. "Études de l'effet laser dans un micro résonateur à modes de Galerie en verre ZBLALiP dopé Erbium". Journal de Physique IV (Proceedings) 12, n.º 5 (junio de 2002): 269–70. http://dx.doi.org/10.1051/jp4:20020156.

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40

Jali, Mohd Hafiz, Hazli Rafis Abdul Rahim, Md Ashadi Md Johari, Mohamad Faizal Baharom, Aminah Ahmad, Haziezol Helmi Mohd Yusof y Sulaiman Wadi Harun. "Optical Microfiber Sensor : A Review". Journal of Physics: Conference Series 2075, n.º 1 (1 de octubre de 2021): 012021. http://dx.doi.org/10.1088/1742-6596/2075/1/012021.

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Abstract Due to numerous benefits such as geometrical simplicity, compact size, high sensitivity, broad detection range, low noise, and high accuracy, optical devices have attracted a lot of interest for sensing applications. It is critical in a variety of sectors, including cultural relic preservation, warehouse products maintenance, manufacturing process control, semiconductor, agriculture, food production storage, environmental control, health industries, chemical and home improvement. It outperforms its electronic equivalent owing to its capacity to function in tough and demanding situations such as combustible surroundings, greater pressure and temperature levels, and the ability to send signals over long distances without electromagnetic interference. Optical fiber sensors are classified based on their operating principles such as interferometers, fiber Bragg gratings (FBG), resonators and whispering galleries modes (WGM). This paper presents a comprehensive review related to the optical microfiber sensor such as its properties, fabrication techniques, evanescent wave, optical micro resonators and recent study on the application of microfiber towards humidity sensing. This review could be beneficial to help other researchers to gain greater view in the field of optical microfiber sensor.

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41

Abdalmalak, Kerlos Atia, Gabriel Santamaria Botello, Mallika Irene Suresh, Enderson Falcón-Gómez, Alejandro Rivera Lavado y Luis Enrique García-Muñoz. "An Integrated Millimeter-Wave Satellite Radiometer Working at Room-Temperature with High Photon Conversion Efficiency". Sensors 22, n.º 6 (21 de marzo de 2022): 2400. http://dx.doi.org/10.3390/s22062400.

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In this work, the design of an integrated 183GHz radiometer frontend for earth observation applications on satellites is presented. By means of the efficient electro-optic modulation of a laser pump with the observed millimeter-wave signal followed by the detection of the generated optical sideband, a room-temperature low-noise receiver frontend alternative to conventional Low Noise Amplifiers (LNAs) or Schottky mixers is proposed. Efficient millimeter-wave to 1550 nm upconversion is realized via a nonlinear optical process in a triply resonant high-Q Lithium Niobate (LN) Whispering Gallery Mode (WGM) resonator. By engineering a micromachined millimeter-wave cavity that maximizes the overlap with the optical modes while guaranteeing phase matching, the system has a predicted normalized photon-conversion efficiency ≈10−1 per mW pump power, surpassing the state-of-the-art by around three orders of magnitude at millimeter-wave frequencies. A piezo-driven millimeter-wave tuning mechanism is designed to compensate for the fabrication and assembly tolerances and reduces the complexity of the manufacturing process.

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42

Konstantinou, Georgia, Karolina Milenko, Kyriaki Kosma y Stavros Pissadakis. "Multiple Light Coupling and Routing via a Microspherical Resonator Integrated in a T-Shaped Optical Fiber Configuration System". Micromachines 9, n.º 10 (15 de octubre de 2018): 521. http://dx.doi.org/10.3390/mi9100521.

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We demonstrate a three-port, light guiding and routing T-shaped configuration based on the combination of whispering gallery modes (WGMs) and micro-structured optical fibers (MOFs). This system includes a single mode optical fiber taper (SOFT), a slightly tapered MOF and a BaTiO3 microsphere for efficient light coupling and routing between these two optical fibers. The BaTiO3 glass microsphere is semi-immersed into one of the hollow capillaries of the MOF taper, while the single mode optical fiber taper is placed perpendicularly to the latter and in contact with the equatorial region of the microsphere. Experimental results are presented for different excitation and reading conditions through the WGM microspherical resonator, namely, through single mode optical fiber taper or the MOF. The experimental results indicate that light coupling between the MOF and the single mode optical fiber taper is facilitated at specific wavelengths, supported by the light localization characteristics of the BaTiO3 glass microsphere, with spectral Q-factors varying between 4.5 × 103 and 6.1 × 103, depending on the port and parity excitation.

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43

Balakireva, Irina V., Igor Yu Blinov, Vladislav I. Pavlov y Nickolay P. Khatyrev. "State of the art and perspectives of the devices with the optical WGM resonators in time and frequency metrology". Izmeritel`naya Tekhnika, n.º 3 (2020): 24–28. http://dx.doi.org/10.32446/0368-1025it.2020-3-24-28.

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One of the most important tasks in the metrological support of time and frequency measurements is a development of an extremely stable narrow-bandwidth laser sources and oscillators of the sets of the equidistant narrow optical spectral lines (the so-called “optical combs”). These devices are necessary for the transmission of the reference frequency signals and for use as part of mobile sources of time and frequency reference signals in optical and microwave spectral ranges. They are also required for precision ultra-high resolution spectroscopy. A promising direction for the creation of highly stable narrow-band lasers and optical combs is the use of miniature optical whispering gallery modes resonators. Recently, research has been actively performed on the properties and manufacturing techniques of such resonators, as well as devices using them. The article provides a review of current research into applications of optical whispering gallery mode resonators in time and frequency metrology. Main advantages and disadvantages of such devices and prospects for their further use are discussed. The authors review in detail some examples of existing laboratory setups of Russian and foreign scientific groups.

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44

Veluthandath, Aneesh V. y Prem B. Bisht. "Identification of Whispering Gallery Mode (WGM) coupled photoluminescence and Raman modes in complex spectra of MoS 2 in Polymethyl methacrylate (PMMA) microspheres". Journal of Luminescence 187 (julio de 2017): 255–59. http://dx.doi.org/10.1016/j.jlumin.2017.03.031.

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45

Anashkina, Elena A., Maria P. Marisova y Alexey V. Andrianov. "Thermo-Optical Control of Raman Solitons in a Functionalized Silica Microsphere". Micromachines 13, n.º 10 (27 de septiembre de 2022): 1616. http://dx.doi.org/10.3390/mi13101616.

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The investigation of optical microcavity solitons is in demand both for applications and basic science. Despite the tremendous progress in the study of microresonator solitons, there is still no complete understanding of all features of their nonlinear dynamics in various regimes. Controlling soliton properties is also of great interest. We proposed and investigated experimentally and theoretically a simple and easily reproducible way to generate Raman solitons with controllable spectral width in an anomalous dispersion region in a functionalized silica microsphere with whispering gallery modes (WGMs) driven in a normal dispersion regime. To functionalize the microsphere, coating (TiO2 + graphite powder) was applied at the pole. The coating is used for effective thermalization of the radiation of an auxiliary laser diode launched through the fiber stem holding the microsphere to control detuning of the pump frequency from exact resonance due to the thermo-optical shift of the WGM frequencies. We demonstrated that the thermo-optical control by changing the power of an auxiliary diode makes it possible to switch on/off the generation of Raman solitons and control their spectral width, as well as to switch Raman generation to multimode or single-mode. We also performed a detailed theoretical analysis based on the Raman-modified Lugiato–Lefever equation and explained peculiarities of intracavity nonlinear dynamics of Raman solitons. All experimental and numerically simulated results are in excellent agreement.

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Marisova, Maria P., Alexey V. Andrianov y Elena A. Anashkina. "Comprehensive Numerical Analysis of Temperature Sensitivity of Spherical Microresonators Based on Silica and Soft Glasses". Sensors 23, n.º 2 (8 de enero de 2023): 717. http://dx.doi.org/10.3390/s23020717.

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In recent years, the use of optical methods for temperature measurements has been attracting increased attention. High-performance miniature sensors can be based on glass microspheres with whispering gallery modes (WGMs), as their resonant frequencies shift in response to the ambient parameter variations. In this work, we present a systematic comprehensive numerical analysis of temperature microsensors with a realistic design based on standard silica fibers, as well as commercially available special soft glass fibers (GeO2, tellurite, As2S3, and As2Se3). Possible experimental implementation and some practical recommendations are discussed in detail. We developed a realistic numerical model that takes into account the spectral and temperature dependence of basic glass characteristics in a wide parameter range. To the best of our knowledge, spherical temperature microsensors based on the majority of the considered glass fibers have been investigated for the first time. The highest sensitivity dλ/dT was obtained for the chalcogenide As2Se3 and As2S3 microspheres: for measurements at room temperature conditions at a wavelength of λ = 1.55 μm, it was as high as 57 pm/K and 36 pm/K, correspondingly, which is several times larger than for common silica glass (9.4 pm/K). Importantly, dλ/dT was almost independent of microresonator size, WGM polarization and structure; this is a practically crucial feature showing the robustness of the sensing devices of the proposed design.

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47

Revelle, Anthony. "De l’autre côté de la barrière. Franchir la frontière entre l’homme et l’animal avec le Roman de Renart". Investir la frontière, n.º 4 (15 de junio de 2021): 29–36. http://dx.doi.org/10.35562/frontieres.599.

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Ces dernières années ont vu se développer de manière exponentielle les travaux sur la frontière entre l’homme et l’animal, vieille question désormais soumise au prisme du posthumanisme. Métaphysique, cette frontière est également matérielle, car toute frontière suppose une appropriation humaine de l’espace. Or que se passe-t-il quand c’est l’animal qui franchit la frontière, qui investit les lieux qui lui ont été barrés par la clôture, et quand l’être humain imagine lui aussi ce qui se passe derrière la barrière – dans le territoire sensoriel de la vie animale ? Dans cet article, j’interroge la césure instable entre l’humain et la bête et ses modes de spatialisation, à travers l’investissement croisé de l’humain dans le territoire animal et de l’animal dans l’espace humain. Je pars pour cela du Roman de Renart, qui met en scène une galerie d’animaux anthropomorphisés évoluant alternativement entre territoire sauvage et espaces domestiqués et passant constamment de traits humains à animaliers. Je propose d’aborder des textes théoriques contemporains sur l’animalité sous l’angle de la littérature médiévale et, suivant l’invitation des auteurs du Renart, de voir notre monde par les yeux d’une bête. À rebours d’une démarche d’objectivité surplombante, j’envisage l’écriture de l’animalité non comme dépassement, mais comme réinvestissement de la frontière entre l’humain et l’animal, par imagination et désappropriation de l’espace.

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Mamadou, ADAME Salifou, ABDOULAYE Djafarou, TCHAOUSSI FOUSSENI Ayouba, TONDRO MAMAN Abdou Madjidou y TENTE Brice. "Modes Et Outils D’Exploitation Des Formations Végétales Etudiées Dans La Commune De Bassila Au Benin". International Journal of Progressive Sciences and Technologies 39, n.º 1 (30 de junio de 2023): 312. http://dx.doi.org/10.52155/ijpsat.v39.1.5399.

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Les formations végétales constituent un écosystème sensible dans la régularisation de la biodiversité. Les modes et outils mis en œuvre dans l’exploitation de ces formations nécessitent une attention particulière. Etudier la dynamique des forêts classées de Pénessoulou et de Bassila dans une perspective de gestion durable et participative est l’objectif principal de la recherche.L’approche méthodologique pour l’atteinte de cet objectif comprend trois étapes à savoir la collecte des données et des informations, leur traitement et l’analyse des résultats obtenus. Le suivi de l'évolution du paysage, des données topographiques, des images satellites Landsat des années 2000, 2010, 2020, et 2063 a été fait ainsi que l’analyse des ordres de régression et de progression des unités d’occupation du sol. La collecte et le traitement des données phytosociologiques ont été faits grâce aux indices de diversité de Shannon (H), d’Equitabilité de Pielou (E) et de la surface terrière moyenne (G). Au total, 231 individus ont été enquêtés grâce à la méthode de choix raisonné afin d’apprécier les facteurs de dégradation de la végétation et l’analyse des résultats a été faite à l’aide du modèle SWOT.Il ressort des résultats obtenus que la forêt galerie, la forêt dense, la forêt claire et savane boisée et la savane arborée et arbustive sont plus dominantes au détriment des formations anthropiques. 03 ordres de régression et progression ont été observés dans la dynamique des unités d’occupation du sol. L’analyse des types phytogéographiques dans la forêt classée de Bassila révèle que les espèces soudaniennes sont les plus abondantes et les dominantes avec les spectres brut et pondéré respectifs de 46 % et 70 %. La formation des forêts denses sèches comporte 116 espèces réparties en 89 genres et 41 familles sur la base de 8 relevés. Les familles les plus représentées sont : les Leguminoseae (24,91 %), les Combretaceae (30,76 %), Chrysobalanaceae (14,80 %) et Scrophulariaceae (14,44 %). La valeur moyenne de l’indice de Shannon est de 2 ± 0,38 bits. Cette valeur élevée de l’indice de Shannon fait de cette formation un milieu favorable pour l’installation de plusieurs espèces. L’indice d’équitabilité de Pielou est de 0,82 ± 0,08. Le coefficient d’Allan est inférieur à 5 à Adjiro et supérieur à 5 à Bassila. En analysant le niveau de pression sur les ressources forestières, il ressort que les agriculteurs et les exploitants de bois d’œuvre reconnaissent que les feux de végétation, l’érosion, la production végétale et l’exploitation de bois d’œuvre sont des facteurs directs responsables de la dégradation de la végétation. Les difficultés observées sont relatives au faible niveau d’organisation des structures locales de gestion des forêts, à l’inadaptation des plans d’aménagement participatif selon les besoins des populations, à l’insuffisance de renforcement des capacités des populations sur la gestion durable des ressources forestières. Face à ces difficultés, un modèle simplifié de Plan d’Aménagement Participatif (PAP) a été proposé. Il s’appuie sur les actions et le renforcement des instruments juridiques de gestion des PAP, sur la capitalisation des actions des projets intervenants sur l’inventaire et les services écosystémiques qu’offrent les forêts, sur le suivi écologique et socioéconomique des forêts et des populations riveraines, etc.Pour rendre opérationnelles ces actions, un projet de 05 ans a été initié pour un montant de 80 000.000 FCFA et est intitulé : « Installation de plantations d’anacardiers greffés à Pénélan ». Il a pour objectif principal de contribuer à la réduction de la pauvreté et à l’amélioration de la sécurité alimentaire de la population de Pénélan et comporte 04 composantes.

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Toropov, Nikita, Gema Cabello, Mariana P. Serrano, Rithvik R. Gutha, Matías Rafti y Frank Vollmer. "Review of biosensing with whispering-gallery mode lasers". Light: Science & Applications 10, n.º 1 (26 de febrero de 2021). http://dx.doi.org/10.1038/s41377-021-00471-3.

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AbstractLasers are the pillars of modern optics and sensing. Microlasers based on whispering-gallery modes (WGMs) are miniature in size and have excellent lasing characteristics suitable for biosensing. WGM lasers have been used for label-free detection of single virus particles, detection of molecular electrostatic changes at biointerfaces, and barcode-type live-cell tagging and tracking. The most recent advances in biosensing with WGM microlasers are described in this review. We cover the basic concepts of WGM resonators, the integration of gain media into various active WGM sensors and devices, and the cutting-edge advances in photonic devices for micro- and nanoprobing of biological samples that can be integrated with WGM lasers.

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50

Banad, Yaser Mike, Syed Mohammad Abid Hasan, Sarah S. Sharif, Georgios Veronis y Manas Ranjan Gartia. "Optical properties and behavior of whispering gallery mode resonators in complex microsphere configurations: Insights for sensing and information processing applications". Nano Select, 10 de enero de 2024. http://dx.doi.org/10.1002/nano.202300184.

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AbstractThis paper delves into the intricate world of whispering gallery mode (WGM) resonators within complex microsphere configurations, exploring their optical properties and behavior. Integrated with optical sensing and processing technology, WGM resonators offer compact size, high sensitivity, rapid response, and tunability. The study investigates the impact of configuration, size, excitation, polarization, and coupling effects on WGM properties. Notable findings include enhanced sensitivity in single microsphere resonators, influence of unequal sphere sizes and excitation locations on WGM modes, and higher quality factors (Q‐factors) in triangular three‐microsphere resonator configurations. Circular polarization was found to elevate Q‐factors, while the nine‐microsphere resonator configuration exhibited increased intensity of dominant WGM peaks with higher laser power, suppressing other peaks. These insights guide the design and optimization of microsphere resonator systems, positioning them for applications in sensing and optical information processing.

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