Journal articles: 'TeraHertz phonons'

1

Renk, K. F., and U. Happek. "Terahertz-phonons: New Phonon Spectroscopies." Physica Scripta T29 (January 1, 1989): 226–29. http://dx.doi.org/10.1088/0031-8949/1989/t29/043.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Ansari, Meenhaz, Subhana Nafees, S. S. Z. Ashraf, and Absar Ahmad. "Terahertz acoustic phonon Cerenkov emission in bilayer graphene." Journal of Applied Physics 132, no. 2 (July 14, 2022): 024303. http://dx.doi.org/10.1063/5.0091369.

Full text

Abstract:

We present a theoretical investigation on the generation of Cerenkov emission of terahertz acoustic phonons in bilayer graphene (BLG) in the presence of a driving dc electric field. We have numerically and analytically studied the Cerenkov phonon emission spectrum, [Formula: see text], and phonon intensity, [Formula: see text], dependence on the phonon frequency [Formula: see text], drift velocity [Formula: see text], electron temperature [Formula: see text], concentration n, and phonon emission angle [Formula: see text] in BLG with and without considering the chirality of the charge carriers. We find that the magnitude of [Formula: see text] increases at larger drift velocities and applied electric fields with the peak of the spectrum shifting toward the higher frequency side. The spectrum magnitude in BLG is found to be much enhanced as compared to conventional 2D semiconductors and transition metal dichalcogenides, which makes it viable for SASER and other practical device applications. The chiral nature of carriers strongly influences the [Formula: see text] behavior and sharpens the spectrum peak but with a decrease in the magnitude. The chirality favors the negative emission spectrum caused by the absorption of acoustic phonons. [Formula: see text] and [Formula: see text] are found to be strongly dependent on temperature but independent of carrier concentration in the equipartition regime. The study is significant from the point of application of BLG as an acousto/optoelectronic device and high-frequency phonon spectrometers.

APA, Harvard, Vancouver, ISO, and other styles

3

Nika, Denis, Evghenii Pokatilov, Vladimir Fomin, Josef Devreese, and Jacques Tempere. "Resonant Terahertz Light Absorption by Virtue of Tunable Hybrid Interface Phonon–Plasmon Modes in Semiconductor Nanoshells." Applied Sciences 9, no. 7 (April 6, 2019): 1442. http://dx.doi.org/10.3390/app9071442.

Full text

Abstract:

Metallic nanoshells have proven to be particularly versatile, with applications in biomedical imaging and surface-enhanced Raman spectroscopy. Here, we theoretically demonstrate that hybrid phonon-plasmon modes in semiconductor nanoshells offer similar advantages in the terahertz regime. We show that, depending on tm,n,nhe doping of the semiconductor shells, terahertz light absorption in these nanostructures can be resonantly enhanced due to the strong coupling between interface plasmons and phonons. A threefold to fourfold increase in the absorption peak intensity was achieved at specific values of electron concentration. Doping, as well as adapting the nanoshell radius, allowed for fine-tuning of the absorption peak frequencies.

APA, Harvard, Vancouver, ISO, and other styles

4

Pavlov, Sergeij G., Heinz Wilhelm Hübers, Nikolay V. Abrosimov, and H. Riemann. "Mono- and Polycrystalline Silicon for Terahertz Intracenter Lasers." Solid State Phenomena 131-133 (October 2007): 579–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.131-133.579.

Full text

Abstract:

The performance of optically pumped terahertz silicon lasers with active media made from mono- and polycrystalline silicon doped by phosphorus has been investigated. The polycrystalline silicon samples consist of grains with a characteristic size distribution in the range from 50 to 500 m. Despite of significant changes of the principal phonon spectrum and increased scattering of phonons at grain boundaries, the silicon laser made from polycrystalline material has a laser threshold and an operation temperature only slightly worse than that of monocrystalline silicon lasers.

APA, Harvard, Vancouver, ISO, and other styles

5

Boldyrev, Kirill N., Boris Z. Malkin, and Marina N. Popova. "Magnetic-Field-Tunable Intensity Transfer from Optically Active Phonons to Crystal-Field Excitations in the Reflection Spectra of the PrFe3(BO3)4 Antiferromagnet." Crystals 12, no. 3 (March 14, 2022): 392. http://dx.doi.org/10.3390/cryst12030392.

Full text

Abstract:

We analyze the field-dependent intensities of the coupled electron-phonon modes observed in the low-temperature far-infrared (terahertz) reflection spectra of PrFe3(BO3)4 and develop a theory based on the Green’s function approach. An excellent agreement between the experimental and theoretical data is achieved. The developed theory of the intensity transfer from phonons to quasi-electronic excitations can be applied to the electron-phonon modes in other compounds, in particular, in magnetodielectric materials, where it can be used to analyze the magnetodielectric response.

APA, Harvard, Vancouver, ISO, and other styles

6

Lanzillotti-Kimura, N. D., A. Fainstein, A. Lemaître, and B. Jusserand. "Nanowave devices for terahertz acoustic phonons." Applied Physics Letters 88, no. 8 (February 20, 2006): 083113. http://dx.doi.org/10.1063/1.2178415.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Makler, Sergio S., M. I. Vasilevskiy, E. V. Anda, D. E. Tuyarot, J. Weberszpil, and H. M. Pastawski. "A source of terahertz coherent phonons." Journal of Physics: Condensed Matter 10, no. 26 (July 6, 1998): 5905–21. http://dx.doi.org/10.1088/0953-8984/10/26/017.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Vasileiadis, Thomas, Juan Sebastian Reparaz, and Bartlomiej Graczykowski. "Phonon transport in the gigahertz to terahertz range: Confinement, topology, and second sound." Journal of Applied Physics 131, no. 18 (May 14, 2022): 180901. http://dx.doi.org/10.1063/5.0073508.

Full text

Abstract:

Transport of heat and hypersound with gigahertz (GHz) to terahertz (THz) phonons is crucial for heat management in electronics, mediating signal processing with microwave radiation, thermoelectrics, and various types of sensors based on nanomechanical resonators. Efficient control of heat and sound transport requires new materials, novel experimental techniques, and a detailed knowledge of the interaction of phonons with other elementary excitations. Wave-like heat transport, also known as second sound, has recently attracted renewed attention since it provides several opportunities for overcoming some of the limitations imposed by diffusive transport (Fourier’s regime). The frequency-domain detection of GHz-to-THz phonons can be carried out in a remote, non-destructive, and all-optical manner. The ongoing development of nanodevices and metamaterials made of low-dimensional nanostructures will require spatially resolved, time-resolved, and anisotropic measurements of phonon-related properties. These tasks can be accomplished with Brillouin light scattering (BLS) and various newly developed variants of this method, such as pumped-BLS. In the near future, pumped-BLS is expected to become useful for characterizing GHz topological nanophononics. Finally, second-sound phenomena can be observed with all-optical methods like frequency-domain thermoreflectance.

APA, Harvard, Vancouver, ISO, and other styles

9

Woerner, Michael, Carmine Somma, Klaus Reimann, Thomas Elsaesser, Igal Brener, John L. Reno, Yuanmu Yang, and Peter Q. Liu. "Terahertz driven amplification of coherent optical phonons in GaAs coupled to metallic dog-bone resonators." EPJ Web of Conferences 205 (2019): 05007. http://dx.doi.org/10.1051/epjconf/201920505007.

Full text

Abstract:

Two-dimensional terahertz spectroscopy on an AlAs/GaAs nanostructure covered by field-enhancing dog-bone resonators shows signatures of coherent optical phonon amplification. Amplification is due to stimulated phonon emission by a terahertz-driven electron current.

APA, Harvard, Vancouver, ISO, and other styles

10

Caldwell, Joshua D., Lucas Lindsay, Vincenzo Giannini, Igor Vurgaftman, Thomas L. Reinecke, Stefan A. Maier, and Orest J. Glembocki. "Low-loss, infrared and terahertz nanophotonics using surface phonon polaritons." Nanophotonics 4, no. 1 (April 13, 2015): 44–68. http://dx.doi.org/10.1515/nanoph-2014-0003.

Full text

Abstract:

AbstractThe excitation of surface-phonon-polariton (SPhP) modes in polar dielectric crystals and the associated new developments in the field of SPhPs are reviewed. The emphasis of this work is on providing an understanding of the general phenomenon, including the origin of the Reststrahlen band, the role that optical phonons in polar dielectric lattices play in supporting sub-diffraction-limited modes and how the relatively long optical phonon lifetimes can lead to the low optical losses observed within these materials. Based on this overview, the achievements attained to date and the potential technological advantages of these materials are discussed for localized modes in nanostructures, propagating modes on surfaces and in waveguides and novel metamaterial designs, with the goal of realizing low-loss nanophotonics and metamaterials in the mid-infrared to terahertz spectral ranges.

APA, Harvard, Vancouver, ISO, and other styles

11

Gao, Liang, John L. Reno, and Sushil Kumar. "Short Barriers for Lowering Current-Density in Terahertz Quantum Cascade Lasers." Photonics 7, no. 1 (January 8, 2020): 7. http://dx.doi.org/10.3390/photonics7010007.

Full text

Abstract:

Scattering due to interface-roughness (IR) and longitudinal-optical (LO) phonons are primary transport mechanisms in terahertz quantum-cascade lasers (QCLs). By choosing GaAs/Al0.10Ga0.90As heterostructures with short-barriers, the effect of IR scattering is mitigated, leading to low operating current-densities. A series of resonant-phonon terahertz QCLs developed over time, achieving some of the lowest threshold and peak current-densities among published terahertz QCLs with maximum operating temperatures above 100 K. The best result is obtained for a three-well 3.1 THz QCL with threshold and peak current-densities of 134 A/cm2 and 208 A/cm2 respectively at 53 K, and a maximum lasing temperature of 135 K. Another three-well QCL designed for broadband bidirectional operation achieved lasing in a combined frequency range of 3.1–3.7 THz operating under both positive and negative polarities, with an operating current-density range of 167–322 A/cm2 at 53 K and maximum lasing temperature of 141 K or 121 K depending on the polarity of the applied bias. By showing results from QCLs developed over a period of time, here we show conclusively that short-barrier terahertz QCLs are effective in achieving low current-density operation at the cost of a reduction in peak temperature performance.

APA, Harvard, Vancouver, ISO, and other styles

12

Rivera, Nicholas, Gilles Rosolen, John D. Joannopoulos, Ido Kaminer, and Marin Soljačić. "Making two-photon processes dominate one-photon processes using mid-IR phonon polaritons." Proceedings of the National Academy of Sciences 114, no. 52 (December 12, 2017): 13607–12. http://dx.doi.org/10.1073/pnas.1713538114.

Full text

Abstract:

Phonon polaritons are guided hybrid modes of photons and optical phonons that can propagate on the surface of a polar dielectric. In this work, we show that the precise combination of confinement and bandwidth offered by phonon polaritons allows for the ability to create highly efficient sources of polariton pairs in the mid-IR/terahertz frequency ranges. Specifically, these polar dielectrics can cause emitters to preferentially decay by the emission of pairs of phonon polaritons, instead of the previously dominant single-photon emission. We show that such two-photon emission processes can occur on nanosecond time scales and can be nearly 2 orders of magnitude faster than competing single-photon transitions, as opposed to being as much as 8–10 orders of magnitude slower in free space. These results are robust to the choice of polar dielectric, allowing potentially versatile implementation in a host of materials such as hexagonal boron nitride, silicon carbide, and others. Our results suggest a design strategy for quantum light sources in the mid-IR/terahertz: ones that prefer to emit a relatively broad spectrum of photon pairs, potentially allowing for new sources of both single and multiple photons.

APA, Harvard, Vancouver, ISO, and other styles

13

Hasegawa, Takayuki, Masaya Marui, and Yoshihito Tanaka. "Electric field dependence of terahertz wave emission in temperature-controlled GaAs epitaxial films." Applied Physics Express 15, no. 5 (April 8, 2022): 051001. http://dx.doi.org/10.35848/1882-0786/ac5fc7.

Full text

Abstract:

Abstract We have investigated the dependence of terahertz wave emissions on the internal electric field in undoped GaAs/n-type GaAs epitaxial structures irradiated by ultrashort laser pulses. The undoped layer has an electric field, the strength of which was controlled by the temperature in addition to the undoped layer thickness. We observed the electric field dependence of the terahertz waveform, and the results were explained by the calculation of the transient dynamics of electrons and phonons under electric fields. Furthermore, we indicated that the terahertz amplitude can be linearly controlled by the electric field strength in a wide electric field range.

APA, Harvard, Vancouver, ISO, and other styles

14

Tani, M., R. Fukasawa, H. Abe, S. Matsuura, K. Sakai, and S. Nakashima. "Terahertz radiation from coherent phonons excited in semiconductors." Journal of Applied Physics 83, no. 5 (March 1998): 2473–77. http://dx.doi.org/10.1063/1.367007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Zhao, C. X., W. Xu, and F. M. Peeters. "Cerenkov emission of terahertz acoustic-phonons from graphene." Applied Physics Letters 102, no. 22 (June 3, 2013): 222101. http://dx.doi.org/10.1063/1.4808392.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Lavor, I. R., Andrey Chaves, F. M. Peeters, and B. Van Duppen. "Tunable coupling of terahertz Dirac plasmons and phonons in transition-metal dichalcogenide-based van der Waals heterostructures." 2D Materials 9, no. 1 (November 24, 2021): 015018. http://dx.doi.org/10.1088/2053-1583/ac37a8.

Full text

Abstract:

Abstract Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons’ properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene’s Fermi energy and changing TMD layer number.

APA, Harvard, Vancouver, ISO, and other styles

17

Fu Pei-Zhen, Hou Bi-Hui, Wang Li, Zhong Ren-Bin, Wang Ya-Li, Zhang Er-Pan, and Jian Yan-Zhen. "Terahertz spectra and soft optical phonons of PbB4O7 crystal." Acta Physica Sinica 59, no. 7 (2010): 4640. http://dx.doi.org/10.7498/aps.59.4640.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Vassant, S., F. Marquier, J. J. Greffet, F. Pardo, and J. L. Pelouard. "Tailoring GaAs terahertz radiative properties with surface phonons polaritons." Applied Physics Letters 97, no. 16 (October 18, 2010): 161101. http://dx.doi.org/10.1063/1.3497645.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Menon, V. M., L. R. Ram-Mohan, W. D. Goodhue, A. J. Gatesman, and A. S. Karakashian. "Role of interface phonons in quantum cascade terahertz emitters." Physica B: Condensed Matter 316-317 (May 2002): 212–15. http://dx.doi.org/10.1016/s0921-4526(02)00461-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Niu, Tianye, Boqi Qiu, Ya Zhang, and Kazuhiko Hirakawa. "Effects of substrate phonon absorption on the resonance behavior of metal–insulator–metal metamaterial terahertz absorbers." Applied Physics Express 14, no. 12 (December 1, 2021): 122007. http://dx.doi.org/10.35848/1882-0786/ac3bd8.

Full text

Abstract:

Abstract We have investigated the effects of substrate phonon absorption on the resonance behavior of metal–insulator–metal (MIM) double-layer metamaterial absorbers (MMAs) in the terahertz (THz) frequency range. A sharp resonant absorption dip is clearly observed for a metamaterial-on-ground-plane (MMOGP) structure fabricated on a semi-insulating (SI) GaAs substrate when THz radiation is incident from the surface metamaterials (MMs) side. However, when the THz is incident from the substrate side to the ground-plane-on-metamaterial (GPOMM) structures fabricated on a SI GaAs substrate, we find that the resonance dip is almost merged into the broad background of acoustic phonon absorption. The resonant absorption is recovered when the GaAs substrate is replaced with a high-resistivity Si substrate. These findings demonstrate that the choice of substrates is very important to suppress the absorption by acoustic phonons absorption in the THz range and achieve high-quality factor resonance.

APA, Harvard, Vancouver, ISO, and other styles

21

Belikov, I., M. Rybin, A. Prikhodko, D. Mikhailov, I. Gayduchenko, A. Shurakov, and G. Goltsman. "Terahertz detector utilizing a SiO₂/Graphene/SiO₂ sandwich suspended at the feed of a planar antenna." Journal of Physics: Conference Series 2086, no. 1 (December 1, 2021): 012048. http://dx.doi.org/10.1088/1742-6596/2086/1/012048.

Full text

Abstract:

Abstract We report on the fabrication of a terahertz detector utilizing a SiO2/graphene/SiO2 sandwich suspended at the planar antenna feed. This design of the detector aims to enhance its sensitivity via weakening of the heat sink between graphene’s phonons and those of the substrate. We achieve complete suspension of the sandwich only in case of a low fill-factor of the antenna feed area. Evaluated DC parameters of the samples are consistent with those reported in the literature. The fabrication process developed is suitable for implementing the detector proposed for signal frequencies up to several terahertz.

APA, Harvard, Vancouver, ISO, and other styles

22

Iwamoto, K., T. Mori, S. Kushibiki, H. Honda, H. Matsumoto, K. Suekuni, M. A. Avila, T. Takabatake, and N. Toyota. "Optical Conductivity of Rattling Phonons in Type-I Clathrates Ba₈Ga₁₆Ge₃₀ and Ba₈Ga₁₆Sn₃₀." Key Engineering Materials 508 (March 2012): 341–46. http://dx.doi.org/10.4028/www.scientific.net/kem.508.341.

Full text

Abstract:

We Review Our Dynamical Property Measurements of Rattling Phonons in Type-I Clathrate Compounds, the Quasi-on-Center Ba8Ga16Ge30 (BGG) and Off-Center Ba8Ga16Sn30 (BGS), Using a Terahertz Time-Domain Spectrometer. The Lowest-Lying Vibrational Modes of Rattling Ba Ions in the Oversized Cage Show Anomalous Temperature Dependence in their Spectra. For BGG, the Temperature Dependence Is Mostly Consistent with a Local Anharmonic Potential Approximation that Predicts Softening towards Low Temperature. On the other Hand, for BGS, a Single Broad Peak of Off-Center Rattling Phonons Splits into Two Subpeaks below 120 K, and, with Further Lowering Temperature, the Spectra Show Anomalous Broadening. While the Splitting Can Be Understood by the Double Well Potential, the Linewidth Broadening Must Be Attributed to some Relevant Interactions with such Excitations as Acoustic Phonons and Doped Carriers.

APA, Harvard, Vancouver, ISO, and other styles

23

Huang, Shenyang, Chaoyu Song, Guowei Zhang, and Hugen Yan. "Graphene plasmonics: physics and potential applications." Nanophotonics 6, no. 6 (October 18, 2016): 1191–204. http://dx.doi.org/10.1515/nanoph-2016-0126.

Full text

Abstract:

AbstractPlasmon in graphene possesses many unique properties. It originates from the collective motion of massless Dirac fermions, and the carrier density dependence is distinctively different from conventional plasmons. In addition, graphene plasmon is highly tunable and shows strong energy confinement capability. Most intriguingly, as an atom-thin layer, graphene and its plasmon are very sensitive to the immediate environment. Graphene plasmons strongly couple to polar phonons of the substrate, molecular vibrations of the adsorbates, and lattice vibrations of other atomically thin layers. In this review, we present the most important advances in graphene plasmonics field. The topics include terahertz plasmons, mid-infrared plasmons, plasmon-phonon interactions, and potential applications. Graphene plasmonics opens an avenue for reconfigurable metamaterials and metasurfaces; it is an exciting and promising new subject in the nanophotonics and plasmonics research field.

APA, Harvard, Vancouver, ISO, and other styles

24

Demsar, Jure, Richard D. Averitt, Antoinette J. Taylor, Won-Nam Kang, Heon Jung Kim, Eun-Mi Choi, and Sung-Ik Lee. "Photoinduced Conductivity Dynamics Studies of MgB2 Thin Films." International Journal of Modern Physics B 17, no. 18n20 (August 10, 2003): 3675–81. http://dx.doi.org/10.1142/s0217979203021605.

Full text

Abstract:

We present the first direct studies of photoinduced Cooper-pair breaking and subsequent superconducting state recovery dynamics by means of femtosecond time-resolved optical-pump terahertz probe spectroscopy focusing on the superconducting state recovery dynamics in MgB 2. The superconducting state recovery proceeds on the timescale of several hundred picoseconds and shows a strong temperature dependence. In particular, upon increasing the temperature the recovery time first decreases, reaches a minimum, followed by a quasi-divergence upon further increasing the temperature towards Tc. Moreover, the recovery time shows virtually no intensity dependence, even though the photoexcitation fluence is changed by over an order of magnitude. This suggests that pair recovery is goverend by a phonon-bottleneck mechanism, where the lifetime of high energy phonons (ℏω > 2Δ) is governed by their anharmonicity.

APA, Harvard, Vancouver, ISO, and other styles

25

Komirenko, S. M., K. W. Kim, V. A. Kochelap, and M. A. Stroscio. "Confinement and amplification of terahertz acoustic phonons in cubic heterostructures." Physica B: Condensed Matter 316-317 (May 2002): 356–58. http://dx.doi.org/10.1016/s0921-4526(02)00506-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Feofilov, S. P., A. A. Kaplyanskii, and M. B. Melnikov. "Transport of terahertz nonequilibrium acoustic phonons in dense corundum ceramics." Physica B: Condensed Matter 219-220 (April 1996): 773–74. http://dx.doi.org/10.1016/0921-4526(95)00881-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Lee, Hovan, Cedric Weber, Manfred Fähnle, and Mostafa Shalaby. "Ultrafast Electron Dynamics in Magnetic Thin Films." Applied Sciences 11, no. 20 (October 19, 2021): 9753. http://dx.doi.org/10.3390/app11209753.

Full text

Abstract:

In past decades, ultrafast spin dynamics in magnetic systems have been associated with heat deposition from high energy laser pulses, limiting the selective access to spin order. Here, we use a long wavelength terahertz (THz) pump–optical probe setup to measure structural features in the ultrafast time scale. We find that complete demagnetization is possible with <6 THz pulses. This occurs concurrently with longitudinal acoustic phonons and an electronic response.

APA, Harvard, Vancouver, ISO, and other styles

28

Kinha, Monu, G. L. Prajapati, Malay Udeshi, Piyush Agarwal, N. Bhargava Ram, and D. S. Rana. "Ultrafast dynamical charge-lattice coupling in rare-earth nickelate thin films studied by time-resolved terahertz spectroscopy." Journal of Physics D: Applied Physics 55, no. 22 (March 3, 2022): 225301. http://dx.doi.org/10.1088/1361-6463/ac5698.

Full text

Abstract:

Abstract Rare-earth nickelates exhibit a rich phase diagram formed by the complex interplay of intertwined and competing energetics of fundamental entities. To unwind the coupling and interaction mechanisms of fundamental entities underneath, time-resolved terahertz (THz) spectroscopy was implemented to understand non-equilibrium carrier and lattice dynamics of epitaxial thin films of La x Eu1−x NiO3 (x = 0, 0.25, 0.50, 1) systems, where x = 0 is insulating while remaining are metallic at room temperature. The THz transmittance of the insulating and metallic phases exhibit contrasting photo-induced phases associated with bi-exponential and mono-exponential relaxation mechanisms, respectively. A pronounced oscillatory feature superimposed on the mono-exponential relaxation manifests only in the metallic phase. As ascribed to the acoustic phonons, the ‘x’ dependent behavior of this feature reveals an inverse relation between the strength of electron–phonon coupling and the magnitude of conductivity. In the insulating state, in contrast, the relaxation time constants are associated with the recovery of charge-ordering and electron–phonon thermalization. This dynamical lattice–charge interaction study demonstrates use of this ultrafast phenomena in nickelate thin films in new generation ultrafast photo-acoustic devices as an alternate to conventional surface acoustic wave device.

APA, Harvard, Vancouver, ISO, and other styles

29

Adamov, Roman B., Daniil Pashnev, Vadim A. Shalygin, Maria D. Moldavskaya, Maxim Ya Vinnichenko, Vytautas Janonis, Justinas Jorudas, et al. "Optical Performance of Two Dimensional Electron Gas and GaN:С Buffer Layers in AlGaN/AlN/GaN Heterostructures on SiC Substrate." Applied Sciences 11, no. 13 (June 29, 2021): 6053. http://dx.doi.org/10.3390/app11136053.

Full text

Abstract:

Terahertz time-domain spectroscopy and Fourier-transform infrared spectroscopy were developed as the method for the investigation of high-frequency characteristics of two-dimensional electron gas and GaN:С buffer layers in AlGaN/AlN/GaN heterostructures grown on a semi-insulating SiC substrate. The reflectance and transmittance spectra of the selected heterostructure layers were studied after the top layers were removed by a reactive ion etching. Results were numerically analyzed using the transfer matrix method taking into account the high-frequency electron conductivity via a Drude model and complex dielectric permittivity of each epitaxial layer via a one-phonon-resonance approximation. Good agreement between the experiment and theory was achieved revealing the temperature dependent electron effective mass in AlGaN/AlN/GaN high electron mobility transistor structures and the small damping factors of optical phonons due to high crystal quality of the epitaxial layers fabricated on the SiC substrate.

APA, Harvard, Vancouver, ISO, and other styles

30

Lynch, Scott T., Alessio De Francesco, Luisa Scaccia, and Alessandro Cunsolo. "Controlling terahertz sound propagation: some preliminary Inelastic X-Ray Scattering result." EPJ Web of Conferences 272 (2022): 01010. http://dx.doi.org/10.1051/epjconf/202227201010.

Full text

Abstract:

The control of sound propagation in materials via the design of their elastic properties is an exciting task at the forefront of Condensed Matter. It becomes especially compelling at terahertz frequencies, where phonons are the primary conveyors of heat flow. Despite the increasing focus on this goal, this field of research is still in its infancy; To achieve a few advances in this field, we performed several Inelastic X-Ray Scattering (IXS) measurements on elementary systems as dilute suspensions of nanoparticles (NPs) in liquids. We found that nanoparticles can effectively impact the sound propagation of the hosting liquid. We also explored the possibility of shaping terahertz sound propagation in a liquid upon confinement on quasi-unidimensional cavities. These results are here reviewed and discussed, and future research directions are finally outlined.

APA, Harvard, Vancouver, ISO, and other styles

31

Feofilov, S. P., A. A. Kaplyanskii, A. B. Kulinkin, and R. I. Zakharchenya. "Optical studies of terahertz phonons dynamics in small-grain polycrystalline corundum." Physica B: Condensed Matter 263-264 (March 1999): 695–97. http://dx.doi.org/10.1016/s0921-4526(98)01445-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Makler, Sergio S., I. Camps, José Weberszpil, and Diana E. Tuyarot. "A double-barrier heterostructure generator of terahertz phonons: many-body effects." Journal of Physics: Condensed Matter 12, no. 13 (March 15, 2000): 3149–72. http://dx.doi.org/10.1088/0953-8984/12/13/322.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Fischer, W. W., K. F. Renk, J. A. Campbell, and U. Happek. "Relaxation of terahertz phonons in mixed crystals exhibiting glass-like properties." Journal of Luminescence 58, no. 1-6 (January 1994): 14–16. http://dx.doi.org/10.1016/0022-2313(94)90351-4.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Venanzi, T., M. Selig, A. Pashkin, S. Winnerl, M. Katzer, H. Arora, A. Erbe, et al. "Terahertz control of photoluminescence emission in few-layer InSe." Applied Physics Letters 120, no. 9 (February 28, 2022): 092104. http://dx.doi.org/10.1063/5.0080784.

Full text

Abstract:

A promising route for the development of opto-electronic technology is to use terahertz radiation to modulate the optical properties of semiconductors. Here, we demonstrate the dynamical control of photoluminescence (PL) emission in few-layer InSe using picosecond terahertz pulses. We observe a strong PL quenching (up to 50%) after the arrival of the terahertz pulse followed by a reversible recovery of the emission on the timescale of 50 ps at [Formula: see text] K. Microscopic calculations reveal that the origin of the photoluminescence quenching is the terahertz absorption by photo-excited carriers: this leads to a heating of the carriers and a broadening of their distribution, which reduces the probability of bimolecular electron-hole recombination and, therefore, the luminescence. By numerically evaluating the Boltzmann equation, we are able to clarify the individual roles of optical and acoustic phonons in the subsequent cooling process. The same PL quenching mechanism is expected in other van der Waals semiconductors, and the effect will be particularly strong for materials with low carrier masses and long carrier relaxation time, which is the case for InSe. This work gives a solid background for the development of opto-electronic applications based on InSe, such as THz detectors and optical modulators.

APA, Harvard, Vancouver, ISO, and other styles

35

Shikata, Jun-ichi, Seigo Ohno, and Hiroaki Minamide. "Terahertz-wave generation from surface phonons at forbidden frequencies of lithium niobate." IEICE Electronics Express 17, no. 11 (June 10, 2020): 20200133. http://dx.doi.org/10.1587/elex.17.20200133.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Xiao-Yong, He, Cao Jun-Cheng, Lü Jing-Tao, and Feng Song-Lin. "Simulation of Confined and Interface Phonons Scattering in Terahertz Quantum Cascade Laser." Chinese Physics Letters 22, no. 12 (November 28, 2005): 3163–65. http://dx.doi.org/10.1088/0256-307x/22/12/050.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Vitiello, Miriam S., Rita C. Iotti, Fausto Rossi, Lukas Mahler, Alessandro Tredicucci, Harvey E. Beere, David A. Ritchie, Qing Hu, and Gaetano Scamarcio. "Non-equilibrium longitudinal and transverse optical phonons in terahertz quantum cascade lasers." Applied Physics Letters 100, no. 9 (February 27, 2012): 091101. http://dx.doi.org/10.1063/1.3687913.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Onishchenko, E. E., V. S. Bagaev, T. I. Galkina, V. V. Zaitsev, and A. I. Sharkov. "New method of detection of terahertz acoustic phonons in quantum well structures." Physica E: Low-dimensional Systems and Nanostructures 12, no. 1-4 (January 2002): 450–53. http://dx.doi.org/10.1016/s1386-9477(01)00323-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Onishchenko, E. E., V. S. Bagaev, and V. V. Zaitsev. "Stimulated emission of terahertz acoustic phonons as a result of action of nonequilibrium phonons upon the localized exciton ensemble." Physica E: Low-dimensional Systems and Nanostructures 13, no. 2-4 (March 2002): 321–24. http://dx.doi.org/10.1016/s1386-9477(01)00548-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Yang, Chi-Yuan, Ping-Chun Wu, Ying-Hao Chu, and Kung-Hsuan Lin. "Generation and coherent control of terahertz acoustic phonons in superlattices of perovskite oxides." New Journal of Physics 23, no. 5 (May 1, 2021): 053009. http://dx.doi.org/10.1088/1367-2630/abf86e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Mizoguchi, K., T. Furuichi, O. Kojima, M. Nakayama, S. Saito, A. Syouji, and K. Sakai. "Intense terahertz radiation from longitudinal optical phonons in GaAs∕AlAs multiple quantum wells." Applied Physics Letters 87, no. 9 (August 29, 2005): 093102. http://dx.doi.org/10.1063/1.2033138.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Liu, Tzu-Ming, Ja-Yu Lu, Hung-Ping Chen, Chung-Chiu Kuo, Meng-Ju Yang, Chih-Wei Lai, Pi-Tai Chou, et al. "Resonance-enhanced dipolar interaction between terahertz photons and confined acoustic phonons in nanocrystals." Applied Physics Letters 92, no. 9 (March 3, 2008): 093122. http://dx.doi.org/10.1063/1.2891062.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Guarnieri, L. C., V. Anjos, and S. S. Makler. "The effect of temperature on a double-barrier generator of terahertz coherent phonons." Physics Procedia 28 (2012): 57–61. http://dx.doi.org/10.1016/j.phpro.2012.03.671.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Cao, J. C., Y. L. Chen, and H. C. Liu. "Effect of optical phonons on the spectral shape of terahertz quantum-well photodetectors." Superlattices and Microstructures 40, no. 2 (August 2006): 119–24. http://dx.doi.org/10.1016/j.spmi.2006.06.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Sydoruk, O., V. Kalinin, and L. Solymar. "Terahertz instability of optical phonons interacting with plasmons in two-dimensional electron channels." Applied Physics Letters 97, no. 6 (August 9, 2010): 062107. http://dx.doi.org/10.1063/1.3479416.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Iotti, Rita Claudia, Fausto Rossi, Miriam Serena Vitiello, Gaetano Scamarcio, Lukas Mahler, and Alessandro Tredicucci. "Impact of nonequilibrium phonons on the electron dynamics in terahertz quantum cascade lasers." Applied Physics Letters 97, no. 3 (July 19, 2010): 033110. http://dx.doi.org/10.1063/1.3464977.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Bannov, N. A., F. T. Vasko, and V. V. Mitin. "Terahertz absorption by electrons and confined acoustic phonons in free-standing quantum wells." Superlattices and Microstructures 18, no. 4 (December 1995): 269. http://dx.doi.org/10.1006/spmi.1995.1111.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Nakayama, M., K. Mizoguchi, O. Kojima, T. Furuichi, A. Mizumoto, S. Saito, A. Syouji, and K. Sakai. "Terahertz radiation from coherent confined optical phonons in GaAs/AlAs multiple quantum wells." physica status solidi (a) 204, no. 2 (February 2007): 518–21. http://dx.doi.org/10.1002/pssa.200673211.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Grigelionis, Ignas, and Irmantas Kašalynas. "Terahertz Spectroscopy of Thermal Radiation from AlGaN/GaN Heterostructure on Sapphire at Low Temperatures." Applied Sciences 10, no. 3 (January 25, 2020): 851. http://dx.doi.org/10.3390/app10030851.

Full text

Abstract:

Terahertz spectroscopy of thermal radiation from electrically pumped AlGaN/GaN structures on sapphire substrate was investigated in this work. Comparison of experimental THz spectroscopy results to theoretical spectra calculations shows that thermal radiation of the sample lattice is the main mechanism causing the emission above T = 155 K, and it is mainly influenced by sapphire substrate. Here, the emission was attributed to the radiative electron transitions in shallow impurities and nitrogen vacancies as well as to radiative decay of longitudinal optical phonons (387 cm - 1 ) in sapphire substrate. We have successfully demonstrated that THz emission spectroscopy can be used to define the temperature at which thermal emission from AlGaN/GaN HEMT structures dominates the emission spectrum.

APA, Harvard, Vancouver, ISO, and other styles

50

Abbasian, Karim, Leili Hayati, and Ali Rostami. "Design of Terahertz Quantum Dot Cascade Laser Using Raman Amplification Process." Advanced Materials Research 622-623 (December 2012): 1474–78. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.1474.

Full text

Abstract:

As we know, quantum cascade lasers (QCLs) are currently the most advanced electrically pumped semiconductor lasers, which emit radiation due to intersubband optical transitions in semiconductor superlattices. Also, quantum cascade laser is one of the best alternatives for reaching the terahertz frequency by semiconductor structures. In this paper, in order to engineer the QCL, effects of Raman inversion as an optical nonlinearity process in active region (QD Hetero structures) of the THz laser has been investigated by using Launda-type three-level system. This would allow suppression of thermally activated optical phonons scattering processes. At the first, the three level QD is designed, where we have considered three Al0.48In0.52As/Ga0.47In0.47As QDs in z direction with the layer sequence of 4/1.5/4/3.5/4 in nanometers. Then, by rate equations in steady-state condition, the laser gain has been calculated.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'TeraHertz phonons'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles