Details of the Researcher

PHOTO

Tsung Tse Lin
Section
Research Institute of Electrical Communication
Job title
Associate Professor
Degree

  • 博士（工学）（東北大学）

  • 修士（電子工程）（国立交通大学）

e-Rad No.
40585155

Education 1

  • Tohoku University　Graduate School of Engineering

Committee Memberships 3

  • IRMMW-THz 2027 LOC

  • TeraTech2023 LOC

  • レーザー学会学術講演会第41回年次大会 プログラム委員会委員

Awards 1

  1. 桜舞賞 研究奨励賞

    2019/03　理化学研究所

Papers 59

  1. Enhanced surface emission in terahertz quantum cascade lasers using plasma layer assisted photonic crystal waveguides Peer-reviewed

    Mingxi Chen, Tsung-Tse Lin, Li Wang, Hideki Hirayama, Chiko Otani

    Frontiers in Photonics　6　2025/06/18

    Publisher: Frontiers Media SA

    DOI： 10.3389/fphot.2025.1614809 　

    eISSN： 2673-6853

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    Introduction: Surface-emitting terahertz quantum cascade lasers (THz QCLs) are highly promising for applications requiring high-quality far-field beams and controlled beam divergence. However, limited brightness and output power in conventional surface-emitting designs remain significant barriers to practical implementation. Although photonic crystal structures and distributed Bragg reflectors have been explored to enhance surface emission, intrinsic limitations in emission area scaling and brightness improvement persist. Thus, new strategies are essential to advance the performance of surface-emitting THz QCLs. Methods: This study proposes a plasma-assisted photonic crystal waveguide design to improve surface emission efficiency in THz QCLs. A three-dimensional TM-mode coupled wave theory (3D TM-mode CWT) model was developed, incorporating effective permittivity enhancement and a self-consistent iterative scheme to accurately simulate optical field distribution and interaction within the structure. Results: Simulations reveal that the introduction of a plasma layer effectively disrupts the optical field symmetry characteristic of conventional double-metal waveguides, promoting vertical emission. Through systematic optimization, a plasma layer thickness of 0.8 μm was identified as having the potential to achieve surface emission efficiencies exceeding those of conventional structures by over two orders of magnitude. This enhancement is realized without significantly increasing fabrication complexity. Discussion: The plasma-assisted photonic crystal waveguide design offers a viable pathway toward realizing high-brightness surface-emitting THz QCLs. Although challenges such as material growth control and thermal management remain, the substantial improvement in surface emission efficiency underscores the potential of this approach for future high-performance terahertz applications.

  2. Terahertz quantum cascade lasers employing convex phonon well Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Optics Express　33　(7)　15292-15292　2025/03/27

    Publisher: Optica Publishing Group

    DOI： 10.1364/oe.553935 　

    eISSN： 1094-4087

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    The 3-level resonant-phonon scheme, a predominant approach for achieving high-temperature operation in terahertz quantum cascade lasers, has recently gained conspicuous progress by purifying the lasing of relevant quantum levels from nonrelevant ones. However, as this 3-level system typically relies on a module architecture with only two quantum wells, the engineering flexibility is limited; for instance, the transparency of injector barriers for the resonant tunneling process is sacrificed to balance the trade-offs between injection selectivity and parasitic leakages through nonrelevant levels. This study presents the convex phonon well concept to expand engineering possibilities for levels of purification. The effectiveness of this concept is initially confirmed by observing lasing at 201 K in experiments.

  3. Molecular beam epitaxial growth and physical properties of AlN/GaN superlattices with an average 50% Al composition Peer-reviewed

    Siqi Li, Pengfei Shao, Xiao Liang, Songlin Chen, Zhenhua Li, Xujun Su, Tao Tao, Zili Xie, Bin Liu, M. Ajmal Khan, Li Wang, T. T. Lin, Hideki Hirayama, Rong Zhang, Ke Wang

    Chinese Physics B　33　(12)　126801-126801　2024/12/01

    Publisher: IOP Publishing

    DOI： 10.1088/1674-1056/ad84cc 　

    ISSN： 1674-1056

    eISSN： 2058-3834

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    Abstract We report molecular beam epitaxial growth and electrical and ultraviolet light emitting properties of (AlN)m/(GaN)n superlattices (SLs), where m and n represent the numbers of monolayers. Clear satellite peaks observed in XRD 2θ–ω scans and TEM images evidence the formation of clear periodicity and atomically sharp interfaces. For (AlN)m/(GaN)n SLs with an average Al composition of 50%, we have obtained an electron density up to 4.48 × 1019 cm−3 and a resistivity of 0.002 Ω⋅cm, and a hole density of 1.83 × 1018 cm−3 with a resistivity of 3.722 Ω⋅cm, both at room temperature. Furthermore, the (AlN)m/(GaN)n SLs exhibit a blue shift for their photoluminescence peaks, from 403 nm to 318 nm as GaN is reduced from n = 11 to n = 4 MLs, reaching the challenging UVB wavelength range. The results demonstrate that the (AlN)m/(GaN)n SLs have the potential to enhance the conductivity and avoid the usual random alloy scattering of the high-Al-composition ternary AlGaN, making them promising functional components in both UVB emitter and AlGaN channel high electron mobility transistor applications.

  4. Monolayer-scale AlN/GaN digital alloys grown by plasma-assisted molecular beam epitaxy Peer-reviewed

    Siqi Li, Xiao Liang, Pengfei Shao, Songlin Chen, Zhenhua Li, Xujun Su, Tao Tao, Zili Xie, M. Ajmal Khan, Li Wang, T. T. Lin, Hideki Hirayama, Bin Liu, Dunjun Chen, Ke Wang, Rong Zhang

    Applied Physics Letters　125　(11)　2024/09/09

    Publisher: AIP Publishing

    DOI： 10.1063/5.0215886 　

    ISSN： 0003-6951

    eISSN： 1077-3118

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    The efficiency of usual AlGaN based deep ultraviolet light-emitting devices is still quite low. The difficulties are basically originated from the fundamental material properties of AlGaN. This work has adopted monolayer-scale (AlN)m/(GaN)n ordered digital alloys (DAs) as alternatives to AlGaN random alloys, m and n are the numbers of monolayers. X-ray diffraction scans have demonstrated clear satellite peaks, verifying good periodicity of AlN/GaN DAs grown by molecular beam epitaxy (MBE), and transmission electron microscopy results have revealed atomically sharp and smooth interfaces and quite precise m:n values agreeing well with designs. The electron densities of Si-doped (AlN)m/(GaN)n DAs with high equivalent Al compositions are significantly higher than those of conventional AlGaN:Si random alloys grown in the same MBE system. Si dopant ionization energies in DAs are only 2–5 meV, much lower than that for usual random alloys. The red shift of the light emission for DAs with thinner AlN barriers has suggested strong coupling between the GaN wells and thus formation of a miniband in a vertical direction. The results have demonstrated the potential of the (AlN)m/(GaN)n DAs as electronically functional alternatives for various device applications.

  5. Photoresponse Linearity and Speed of an InP-Based Asymmetric-Dual-Grating-Gate HEMT Plasmonic Detector with Respect to Incident THz Radiation Intensity

    M. Nagatsu, K. Narita, Y. Takida, H. Minamide, T.-T. Lin, T. Suemitsu, T. Otsuji, A. Satou

    2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)　1-2　2024/09/01

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz60956.2024.10697615 　

  6. 300-GHz-Band Operation of UTC-PD-Integrated HEMT Photonic Double-Mixer

    Tsung-Tse Lin, Shota Horiuchi, Mitsuki Watanabe, Shinnosuke Uchigasaki, Koichi Tamura, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)　1-2　2024/09/01

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz60956.2024.10697824 　

  7. A fast and sensitive THz rectenna detector working with zero-bias based on the 2D Dirac-Semimetal/Insulator heterostructure

    Chao Tang, Koichi Tamura, Aoi Hamada, Hiroyoshi Kudo, Shinnosuke Uchigasaki, Yuma Takida, Hiroaki Minamide, Tsung-Tse Lin, Akira Satou, Taiichi Otsuji

    JSAP-Optica Joint Symposia 2024 Abstracts　18p_B2_3-18p_B2_3　2024

    Publisher: Optica Publishing Group

    DOI： 10.1364/jsapo.2024.18p_b2_3 　

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    In this study, we developed a fast and sensitive terahertz (THz) detector using a Bi2Se3/h-BN heterostructure rectenna that enables detection without a cathode-anode bias. The fabrication process involved synthesizing β-Bi2Se3 via vapor-controlled liquid phase growth and h-BN via chemical vapor deposition [1]. The Bi2Se3 flake were cleaved and transferred onto a Si/SiO2 substrate, followed by the deposition of anode electrodes and the hot transfer method to stack an h-BN flake, completing the fabrication with cathode and anode electrodes and a bow-tie antenna with metal pads. For THz detection, we employed a 0.95-THz, 500-mW-peak injection-seeded THz parametric generator (is-TPG) as the light source [2], with anode and cathode electrodes connected through a bias tee using a GSG RF probe (Fig. 1). We observed a THz photovoltage peak of 20 mV at an applied electric field of 0.25 V/nm, with a 200-ps full width at half maximum (FWHM). This resulted in a responsivity of 40 mV/W under a 50-Ω load (equivalent to 400 V/W under a 50-kΩ load) and a response time of 100 ps (equivalent to 10 Gbps) at room temperature. Remarkably, we also achieved a responsivity of 20 mV/W at zero bias with the same response speed (Fig. 2). The asymmetry in the peak photovoltage with respect to the applied bipolar electric field is attributed to the asymmetric Dirac conical dispersions of Bi2Se3, highlighting the potential for passive, high-speed THz detection using 2D semimetal devices.

  8. Bi<inf>2</inf>Se<inf>3</inf>/h-BN Heterostructure Rectenna for fast and Sensitive THz Detection

    Chao Tang, Koichi Tamura, Aoi Hamada, Hiroyoshi Kudo, Shinnosuke Uchigasaki, Yuma Takida, Hiroaki Minamide, Tsung Tse Lin, Akira Satou, Taiichi Otsuji

    Device Research Conference - Conference Digest, DRC　2024

    DOI： 10.1109/DRC61706.2024.10605270 　

    ISSN： 1548-3770

  9. Fast and Sensitive Terahertz Detection Based on Novel Insulator/Dirac-Semimetal Heterostructures

    Chao Tang, Koichi Tamura, Aoi Hamada, Hiroyoshi Kudo, Shinnosuke Uchigasaki, Yuma Takida, Hiroaki Minamide, Tsung Tse Lin, Akira Satou, Taiichi Otsuji

    International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz　2024

    DOI： 10.1109/IRMMW-THz60956.2024.10697591 　

    ISSN： 2162-2027

    eISSN： 2162-2035

  10. Synthesis of Bi2Se3 and its application to sensitive and fast THz detection

    Chao Tang, Koichi Tamura, Aoi Hamada, Hiroyoshi Kudo, Shinnosuke Uchigasaki, Yuma Takida, Hiroaki Minamide, Hirokazu Fukidome, Tsung Tse Lin, Akira Satou, Taiichi Otsuji

    Proceedings of SPIE - The International Society for Optical Engineering　13141　2024

    DOI： 10.1117/12.3028676 　

    ISSN： 0277-786X

    eISSN： 1996-756X

  11. Gate-readout and a 3D rectification effect for giant responsivity enhancement of asymmetric dual-grating-gate plasmonic terahertz detectors Peer-reviewed

    Akira Satou, Takumi Negoro, Kenichi Narita, Tomotaka Hosotani, Koichi Tamura, Chao Tang, Tsung-Tse Lin, Paul-Etienne Retaux, Yuma Takida, Hiroaki Minamide, Tetsuya Suemitsu, Taiichi Otsuji

    Nanophotonics　12　(23)　4283-4295　2023/11/02

    Publisher: Walter de Gruyter GmbH

    DOI： 10.1515/nanoph-2023-0256 　

    ISSN： 2192-8606

    eISSN： 2192-8614

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    Abstract We experimentally investigated the asymmetric dual-grating-gate plasmonic terahertz (THz) detector based on an InGaAs-channel high-electron-mobility transistor (HEMT) in the gate-readout configuration. Throughout the THz pulse detection measurement on the fabricated device, we discovered a new detection mechanism called the “3D rectification effect” at the positive gate bias application, which is a cooperative effect of the plasmonic nonlinearities in the channel with the diode nonlinearity in the heterobarrier between the InGaAs channel layer and the InAlAs spacer/carrier-supply/barrier layers, resulting in a giant enhancement of the detector responsivity. We also found that an undesired long-tail waveform observed on the temporal pulse photoresponse of the device is due to trapping of carriers to the donor levels in the silicon δ-doped carrier-supply layer when they tunnel through the barrier to the gate and can be eliminated completely by introducing the so-called inverted-HEMT structure. The internal current responsivity and noise-equivalent power are estimated to be 0.49 A/W (with the equivalent voltage responsivity of 4.9 kV/W with a high output impedance of 10 kΩ) and 196 pW/√Hz at 0.8 THz. These results pave the way towards the application of the plasmonic THz detectors to beyond-5G THz wireless communication systems.

  12. Efficient Optical-to-sub-THz Carrier Frequency Down-Conversion by UTC-PD-Integrated HEMT

    Tsung-Tse Lin, Mitsuki Watanabe, Dai Nagajima, Keisuke Kasai, Masato Yoshida, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    2023 International Topical Meeting on Microwave Photonics (MWP)　1-4　2023/10/15

    Publisher: IEEE

    DOI： 10.1109/mwp58203.2023.10416637 　

  13. Utilizing High-Intensity Optical Subcarrier Signal for Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer International-journal Invited Peer-reviewed

    T.-T. Lin, D. Nakajima, K. Nishimura, M. Watanabe, K. Kasai, M. Yoshida, T. Suemitsu, T. Otsuji, A. Satou

    2023 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)　1　(1)　1-2　2023/09/17

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz57677.2023.10299383 　

  14. Interdiffusion limiting on self-consistent optical gain in terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Mingxi Chen, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Applied Physics Express　16　(7)　072004-072004　2023/07/01

    Publisher: IOP Publishing

    DOI： 10.35848/1882-0786/ace3a4 　

    ISSN： 1882-0778

    eISSN： 1882-0786

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    Abstract In this study, the physical picture of imperfect interfaces is characterized by two terms of in-plane roughness and out-plane interdiffusion. The corresponding scattering is quantified using the nonequilibrium Green’s function model by setting an additional self-energy, and then the impact of scattering strength on GaAs/Al0.3Ga0.7As 2-well terahertz quantum cascade laser performance is investigated. It shows that the interdiffusion scattering term can lead to a maximum reduction of approximately 30% in self-consistent optical gain at a temperature of 300 K. The decrease of population inversion, rather than the broadening linewidth of radiation transition, is the primary factor contributing to the gain degradation. By excluding the effect of band structure deformation caused by interdiffusion in advance, the main cause for the reduction in population inversion is identified as the decoherence of resonant-tunneling injection resulting from interdiffusion scattering.

  15. Clean three-level direct-phonon injection terahertz quantum cascade laser Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Applied Physics Letters　122　(22)　221103　2023/05/29

    Publisher: AIP Publishing

    DOI： 10.1063/5.0138948 　

    ISSN： 0003-6951

    eISSN： 1077-3118

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    For terahertz quantum cascade lasers employing the nonalignment injection scheme via direct-phonon resonance, this study presents the crucial effect of parasitic absorption in the narrow module architecture based on only two quantum wells. The optical gain can be restricted to small (or negative) values even at the low temperature. To address this issue, a suppression strategy by increasing the injection energy is used to isolate the relevant levels. The feasibility of this strategy is experimentally demonstrated by observing lasing at 194 K.

  16. Terahertz quantum cascade laser considering compositional interdiffusion effect Peer-reviewed

    Li Wang, Tsung-Tse Lin, Mingxi Chen, Ke Wang, Hideki Hirayama

    Applied Physics Express　16　(3)　032007-032007　2023/03/31

    Publisher: IOP Publishing

    DOI： 10.35848/1882-0786/acc568 　

    ISSN： 1882-0778

    eISSN： 1882-0786

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    Abstract This study presents an experimental demonstration of the crucial role of compositional interdiffusion at interfaces in GaAs/AlGaAs alternating superlattices for developing the terahertz quantum cascade lasers operating at high temperatures. By growing GaAs/Al0.3Ga0.7As superlattices using the molecular beam epitaxy technique, an aluminum interdiffusion width of 0.95 nm (equivalent to ∼3.4 monolayers) is estimated. Incorporating this interdiffusion width as an additional design parameter has resulted in a 20 K improvement in the maximum operating temperature of the laser. To quantify the magnitude of the interdiffusion scattering effects on electron dynamics, an independent self-energy that functions based on the axial correlation length is introduced in the non-equilibrium Green’s function model. It clarifies that changes in the lifetime of quantum states and also the population fractions are primarily influenced by the deformation of wave functions at the injector when the interfaces become interdiffused.

  17. Doping study of two-well resonant-phonon terahertz quantum cascade lasers part I: doping profile dependence Peer-reviewed

    Teppei Miyoshi, Kai Xi (Cathy) Wang, Tsung-Tse Lin

    Japanese Journal of Applied Physics　62　(3)　032002-032002　2023/03/21

    Publisher: IOP Publishing

    DOI： 10.35848/1347-4065/acbdd8 　

    ISSN： 0021-4922

    eISSN： 1347-4065

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    Abstract The influence of impurity doping on GaAs-based two-well resonant-phonon terahertz quantum cascade lasers is investigated theoretically, and efficient doping schemes are discussed. By using the rate equation model, the impacts of dopant amount, position, and distribution on the performance of a high-performance device is simulated focusing on a single module. The calculated optical gain is found to have a peak over the range of sheet doping density from 1.0 × 1010 to 1.0 × 1012 cm−2 in all eight doping conditions examined in this work. Among these patterns, the devices with the undoped condition and homogeneous-doping in phonon-wells mark high optical gain, and the latter is also resistant against the detuning of subband alignment due to band-bending under the high doping conditions. Furthermore, based on the simulation results, a modulation doping scheme whose active cores include both doped and undoped modules is suggested and discussed.

  18. M-plane GaN terahertz quantum cascade laser structure design and doping effect for resonant-phonon and phonon-scattering-injection schemes

    Ye, F., Wang, Y., Wang, L., Lin, T.-T., Zeng, F., Ji, Y., Zhang, J., Liu, F., Hirayama, H., Wang, K., Shi, Y., Zheng, Y., Zhang, R.

    Scientific Reports　13　(1)　2023

    DOI： 10.1038/s41598-023-38627-3 　

    ISSN： 2045-2322

  19. Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer by High-Intensity Optical Subcarrier Signal

    Dai Nakajima, Kazuki Nishimura, Mitsuki Watanabe, Tsung-Tse Lin, Keisuke Kasai, Masato Yoshida, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    Optical Fiber Communication Conference (OFC) 2023　2023

    Publisher: Optica Publishing Group

    DOI： 10.1364/ofc.2023.m3d.7 　

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    We experimentally investigate the effect of high-intensity subcarrier signal input to the UTC-PD-integrated HEMT working for optical-to-wireless carrier frequency down-conversion on enhancement of its double-mixing conversion gain. The fabricated UTC-PD-integrated HEMT demonstrated the linear increase in the conversion gain by up to +7 dB with increasing the subcarrier signal intensity without saturation, and the conversion gain enhancement of +6.8 dB from -51.0 dB to -44.2 dB was achieved.

  20. Optical gain reduction caused by nonrelevant subbands in narrow-period terahertz quantum cascade laser designs Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Scientific Reports　12　(1)　22228　2022/12/23

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1038/s41598-022-25139-9 　

    ISSN： 2045-2322

    eISSN： 2045-2322

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    Abstract The recent designs of terahertz quantum cascade lasers usually employ the short periodic length and also the tall barriers for high-temperature operation. In this work, the effect of high-energy lying non-relevant subbands is studied based on nonequilibrium Green’s function formalisms model, demonstrating those subbands are probable to play a minor role on the population inversion, but play a major role on the optical gain at high temperatures. The phenomenon can be ascribed to the appearance of leakages crossing neighboring periods via sequential resonant tunneling, and those leakages are inherently created by the specific features of the two-well configuration in this design that the phonon well should be wide enough for performing the phonon scattering to depopulate the lower-laser subband. The narrower periodic length design can strengthen this inter-period leakage. A parasitic absorption between the first high-lying nonrelevant subbands from two laser wells can closely overlap the gain shape and thus significantly reduce the peak gain.

  21. Increasing the output power of a heavily doped terahertz quantum cascade laser by avoiding the subband misalignment Peer-reviewed

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Teppei Miyoshi, Hideki Hirayama

    Journal of Applied Physics　132　(17)　173101-173101　2022/11/07

    Publisher: {AIP} Publishing

    DOI： 10.1063/5.0106751 　

    ISSN： 0021-8979 1089-7550

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    <jats:p> A significant enhancement in the output power of a GaAs-based terahertz quantum cascade laser (THz QCL) was achieved by implementing a relatively high impurity doping concentration. The QC structure was precisely designed using the nonequilibrium green function method by considering the band bending effect caused by a higher doping concentration. This enabled us to avoid the subband misalignment induced by the strong band bending effect, to provide efficient carrier transport even at high doping concentrations, and to improve the output power. The maximum output power of a GaAs/Al<jats:sub>0.16</jats:sub>Ga<jats:sub>0.84</jats:sub>As 3.5 THz-band QCL at 10 K was enhanced from 390 to 600 mW by increasing the doping concentration at the depopulation layers from 6 × 10<jats:sup>16</jats:sup> to 1.2 × 10<jats:sup>17</jats:sup> cm<jats:sup>−3</jats:sup>. The average power of 21 mW was achieved by implementing the appropriate pulse drive conditions. </jats:p>

  22. Nonrelevant quantum levels effecting on the current in 2-well terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Scientific Reports　12　(1)　17378　2022/10/17

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1038/s41598-022-22396-6 　

    ISSN： 2045-2322

    eISSN： 2045-2322

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    Abstract Recent renewed operating temperatures in terahertz quantum cascade lasers emphasize on narrowing the periodic length in a 2-well resonant-phonon design for a clean quantum level structure, in which the depopulation energy is significantly higher than one longitudinal phonon. In this study, various depopulation energies (small and large) are engineered in a 2-well design; the effect of the high-lying nonrelevant levels on the currents are systematically studied by using the non-equilibrium Green’s function method. The engineering of the depopulation energy is unable to avoid the formation of leakage channels, which are activated within at least three neighboring periods via sequential close tunneling. However, a large depopulation energy relaxes the thermal backfilling process; as a result, the net leakages at high temperatures can be significantly suppressed. In addition, pre-alignment remains a critical issue in the design when using a large depopulation energy, which requires improved engineering for the barriers to obtain better laser dynamics.

  23. Room-temperature optical gain in terahertz quantum cascade lasers based on GaAs/AlGaAs, GaN/AlGaN, ZnO/ZnMgO

    Li Wang, Tsung-Tse Lin, Thomas Grange, Ke Wang, Hideki Hirayama

    2022 28th International Semiconductor Laser Conference (ISLC)　2022/10/16

    Publisher: IEEE

    DOI： 10.23919/islc52947.2022.9943321 　

  24. 1.39- Watt Operation of THz Quantum Cascade Laser with Highly Doped Depopulation Layers

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    2022 28th International Semiconductor Laser Conference (ISLC)　2022/10/16

    Publisher: IEEE

    DOI： 10.23919/islc52947.2022.9943475 　

  25. Nonrelevant quantum levels limited laser dynamic in narrow-period terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Japanese Journal of Applied Physics　61　(10)　102003-102003　2022/10/01

    Publisher: {IOP} Publishing

    DOI： 10.35848/1347-4065/ac8c0e 　

    ISSN： 0021-4922 1347-4065

    eISSN： 1347-4065

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    Abstract The fundamental challenges faced by terahertz quantum cascade lasers are the operations below room temperature, and the recent improved operating temperatures are actually based on the narrow-period designs (2-well resonant-phonon scheme). In this study, we address the critical effect of nonrelevant high-confined quantum levels on the laser threshold current in such designs, i.e. at high temperatures, the resonant-tunneling channels passing through neighboring periods via those levels can dominantly increase the laser threshold current. As a result, the laser dynamics significantly shrink to zero even at 270 K. The channels cannot be easily eliminated as they are derived from the specific configuration of a two-quantum-well periodic structure, in which the width of the period is narrow, and the nonrelevant levels from the lower-well are confined down in energy. It is reasonable to suppress the current flowing across those levels by narrowing the lower-well further, but an appropriate balance of its thickness is essential.

  26. Step-flow growth of Al droplet free AlN epilayers grown by plasma assisted molecular beam epitaxy Peer-reviewed

    Pengfei Shao, Siqi Li, Zhenhua Li, Hui Zhou, Dongqi Zhang, Tao Tao, Yu Yan, Zili Xie, Ke Wang, Dunjun Chen, Bin Liu, Youdou Zheng, Rong Zhang, Tsungtse Lin, Li Wang, Hideki Hirayama

    Journal of Physics D: Applied Physics　55　(36)　364002-364002　2022/09/08

    Publisher: {IOP} Publishing

    DOI： 10.1088/1361-6463/ac79dd 　

    ISSN： 0022-3727 1361-6463

    eISSN： 1361-6463

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    Abstract We have investigated an Al modulation epitaxy (AME) method to obtain step-flow growth of Al droplet free AlN layers by plasma assisted molecular beam epitaxy (MBE). At the usual growth temperature of (Al)GaN/AlN heterostructures, Al atom migration and desorption rate are very low and consequently it is very difficult to avoid the formation of Al droplets on AlN growth front by conventional MBE growth method. By adopting the AME growth method, such a difficulty has been effectively overcome and step flow growth mode of AlN has been clearly observed. By optimizing the AME growth time sequence, namely, AlN growth time and N radical beam treatment time, Al droplet free AlN layers with step flow growth characteristics have been obtained, with atomic flat surfaces and an average atomic step width of ∼118 nm at 970 °C–1000 °C, which is still suitable to grow (Al)GaN/AlN heterostructures by MBE.

  27. High Doping Concentration and Variable Al Composition THz Quantum Cascade Lasers with 1.39-Watt Operation

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)　2022/08/28

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz50927.2022.9895547 　

  28. Over One Watt Output Power Terahertz Quantum Cascade Lasers by Using High Doping Concentration and Variable Barrier‐Well Height Peer-reviewed

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    physica status solidi (RRL) – Rapid Research Letters　16　(7)　2200033-2200033　2022/07

    Publisher: Wiley

    DOI： 10.1002/pssr.202200033 　

    ISSN： 1862-6254 1862-6270

    eISSN： 1862-6270

  29. Surface-emitting photonic crystal terahertz quantum cascade laser adopting uniform triangular prism photonic crystal with a double-metal waveguide Peer-reviewed

    Joosun Yun, Tsung-Tse Lin, Hideki Hirayama

    Japanese Journal of Applied Physics　61　(6)　062001-062001　2022/06/01

    Publisher: {IOP} Publishing

    DOI： 10.35848/1347-4065/ac5a00 　

    ISSN： 0021-4922 1347-4065

    eISSN： 1347-4065

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    Abstract Herein, we investigate surface-emitting photonic crystal terahertz quantum cascade lasers adopting double metal waveguide for high light extraction efficiency by utilizing finite-difference time-domain and filter diagonalization method. For the ease of fabrication and scalability of beam power, only a typical uniform 2D unit cell with triangular lattice and connected metal electrodes are considered in this study. Cylinder or uniform triangular prism photonic crystals are adopted as resonators within the selected unit cell structure. Candidate ${\rm{\Gamma } }$-point modes for efficient surface-normal emission are searched based on the unit cell analysis as a first step. After that, far-field, field distribution, and light-extraction efficiency are calculated to verify the candidate modes’ suitability by deploying 15(16) × 15 unit cells. Extracted results show that the surface-emitting quantum cascade lasers with triangular prism photonic crystal slabs have the possibility to attain high light-extraction efficiency with Gaussian beam shape even with compact chip size and high active region occupancy.

  30. Limitation of parasitic absorption in designs of three-state terahertz quantum cascade lasers with direct-phonon injection Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Applied Physics Express　15　(5)　052002-052002　2022/05/01

    Publisher: {IOP} Publishing

    DOI： 10.35848/1882-0786/ac4e26 　

    ISSN： 1882-0778 1882-0786

    eISSN： 1882-0786

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    Abstract To maximize the population inversion in terahertz quantum cascade lasers for high-temperature operation, the scheme of electron injection following direct-phonon emission is more attractive than the common way via resonant tunneling. If this direct-phonon injection can be realized within a simple quantum structure (only three quantum states), much higher optical gain is expected even at room temperature. However, the attempts of this design in experiments are full of challenges. In this work, the non-equilibrium Green’s function method is introduced to draw a full picture of the quantum transport in this design. It demonstrates that the optical gain is strictly limited by a parasitic absorption from one specific high-lying state. Moreover, a strategy is proposed to avoid this limitation.

  31. Over 1 Watt THz QCLs with high doping concentration and variable Al composition in active structure

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    Conference on Lasers and Electro-Optics　2022

    Publisher: Optica Publishing Group

    DOI： 10.1364/cleo_si.2022.ss2d.6 　

    More details Close

    A 1.31 W peak power and 52 mW average power THz QCL is presented by variable Al composition active structure with high doping concentration based on NEGF method design. Device has thick growth active layers and large mesa size with the consideration of heat dissipation.

  32. Leakages suppression by isolating the desired quantum levels for high-temperature terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Tsung-Tse Lin, Mingxi Chen, Ke Wang, Hideki Hirayama

    Scientific Reports　11　(1)　23634　2021/12

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1038/s41598-021-02301-3 　

    ISSN： 2045-2322

    eISSN： 2045-2322

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    Abstract The key challenge for terahertz quantum cascade lasers (THz-QCLs) is to make it operating at room-temperature. The suppression of thermally activated leakages via high lying quantum levels is emphasized recently. In this study, we employ the advanced self-consistent method of non-equilibrium Green’s function, aiming to reveal those kinds of leakages in the commonly used THz-QCL designs based on 2-, 3- and 4-quantum well. At the high temperature of 300 K, if all the confined high lying quantum levels and also the continuums are included within three neighboring periods, leakages indeed possess high fraction of the total current (21%, 30%, 50% for 2-, 3- and 4-quantum well designs, respectively). Ministep concept is introduced to weaken those leakage channels by isolating the desired levels from high lying ones, thus the leakages are well suppressed, with corresponding fractions less than 5% for all three designs.

  33. Engineering of electron–longitudinal optical phonon coupling strength in m-plane GaN terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ming-Xi Chen, Ke Wang, Hideki Hirayama

    Applied Physics Express　14　(11)　112003-112003　2021/11/01

    Publisher: {IOP} Publishing

    DOI： 10.35848/1882-0786/ac2a02 　

    ISSN： 1882-0778 1882-0786

    eISSN： 1882-0786

  34. Over 1 Watt THz QCLs with high doping concentration and variable Al composition in active structure

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    2021 27th International Semiconductor Laser Conference (ISLC)　2021/10/10

    Publisher: IEEE

    DOI： 10.1109/islc51662.2021.9615737 　

  35. Plasma assisted molecular beam epitaxy growth mechanism of AlGaN epilayers and strain relaxation on AlN templates Peer-reviewed

    Zhenhua Li, Pengfei Shao, Yaozheng Wu, Genjun Shi, Tao Tao, Zili Xie, Peng Chen, Yugang Zhou, Xiangqian Xiu, Dunjun Chen, Bin Liu, Ke Wang, Youdou Zheng, Rong Zhang, Tsungtse Lin, Li Wang, Hideki Hirayama

    Japanese Journal of Applied Physics　60　(7)　075504-075504　2021/07/01

    Publisher: {IOP} Publishing

    DOI： 10.35848/1347-4065/ac0bed 　

    ISSN： 0021-4922 1347-4065

    eISSN： 1347-4065

  36. Development of High Power Terahertz Quantum Cascade Lasers by Reducing Leakage Current Using Non-Equilibrium Green’s Function Method Peer-reviewed

    Tsung-Tse LIN, Li WANG, Ke WANG, Hideki HIRAYAMA

    The Review of Laser Engineering　48　(5)　250-250　2020

    Publisher: Laser Society of Japan

    DOI： 10.2184/lsj.48.5_250 　

    ISSN： 0387-0200 1349-6603

    eISSN： 1349-6603

  37. Short-period scattering-assisted terahertz quantum cascade lasers operating at high temperatures Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    Scientific Reports　9　(1)　9446　2019/12

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1038/s41598-019-45957-8 　

    ISSN： 2045-2322

    eISSN： 2045-2322

  38. Optimization of THz QCLs by Suppressing a Leakage Current via High Energy States

    Tsung-Tse Lin, Ke Wang, Li Wang, Hideki Hirayama

    2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)　2019/09

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz.2019.8873833 　

  39. Parasitic transport paths in two-well scattering-assisted terahertz quantum cascade lasers Peer-reviewed

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    Applied Physics Express　12　(8)　082003-082003　2019/08/01

    Publisher: {IOP} Publishing

    DOI： 10.7567/1882-0786/ab2b56 　

    ISSN： 1882-0778 1882-0786

    eISSN： 1882-0786

  40. Optimization of terahertz quantum cascade lasers by suppressing carrier leakage channel via high-energy state Peer-reviewed

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Hideki Hirayama

    Applied Physics Express　11　(11)　112702-112702　2018/11/01

    Publisher: {IOP} Publishing

    DOI： 10.7567/apex.11.112702 　

    ISSN： 1882-0778 1882-0786

    eISSN： 1882-0786

  41. High output power THz quantum cascade lasers and their temperature dependent performance,高输出功率太赫兹量子级联激光器与温度特性 Peer-reviewed

    Lin, T.-T., Wang, K., Wang, L., Hirayama, H.

    Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves　37　(5)　513-517　2018/10

    DOI： 10.11972/j.issn.1001-9014.2018.05.001 　

    ISSN： 1001-9014

  42. Broadening mechanisms and self-consistent gain calculations for GaN quantum cascade laser structures Peer-reviewed

    Ke Wang, Thomas Grange, Tsung-Tse Lin, Li Wang, Zolt{\'{a } }n, J{\'{e } }hn, Stefan Birner, Joosun Yun, Wataru Terashima, Hideki Hirayama

    Applied Physics Letters　113　(6)　061109-061109　2018/08/06

    Publisher: {AIP} Publishing

    DOI： 10.1063/1.5029520 　

    ISSN： 0003-6951 1077-3118

    eISSN： 1077-3118

  43. Controlling loss of waveguides for potential GaN terahertz quantum cascade lasers by tuning the plasma frequency of doped layers Peer-reviewed

    Ke Wang, Tsung-Tse Lin, Li Wang, Wataru Terashima, Hideki Hirayama

    Japanese Journal of Applied Physics　57　(8)　081001-081001　2018/08/01

    Publisher: {IOP} Publishing

    DOI： 10.7567/jjap.57.081001 　

    ISSN： 0021-4922 1347-4065

    eISSN： 1347-4065

  44. Variable Barrier Height AlGaAs/GaAs Quantum Cascade Laser Operating at 3.7 THz Peer-reviewed

    Tsung-Tse Lin, Hideki Hirayama

    physica status solidi (a)　215　(8)　1700424-1700424　2018/04

    Publisher: Wiley

    DOI： 10.1002/pssa.201700424 　

    ISSN： 1862-6300

  45. Waveguide design for GaN/AlGaN terahertz quantum cascade lasers

    Ke Wang, Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    JSAP-OSA Joint Symposia 2017 Abstracts　2017

    Publisher: Optica Publishing Group

    DOI： 10.1364/jsap.2017.7a_a409_5 　

    More details Close

    III-nitrides which have much larger phonon energies (91meV in GaN) can in principle allow for terahertz quantum cascade lasers (THz QCLs) to operate at higher temperatures than GaAs based THz QCLs[1-2], in which the thermally activated phonon scattering depopulation and backfilling are limiting THz lasing at &lt;200 K. GaN THz-QCLs would be key coherent sources in the unexplored terahertz frequency range of 5-12 THz, at which GaAs THz-QCLs are not able to work due to the Reststrahlen band.

  46. 250 mW output power operation of GaAs-based THz quantum cascade lasers

    Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    JSAP-OSA Joint Symposia 2017 Abstracts　2017

    Publisher: Optica Publishing Group

    DOI： 10.1364/jsap.2017.7a_a409_6 　

    More details Close

    THz quantum cascade lasers (QCLs) [1,2] are promising high output power semiconductor THz sources to over Watt order peak power [3] with narrow bandwidth. It is still quite limited for the THz applications caused by the large cryogenic system and low duty cycle with low output power at high operation temperature. Output power is one of the most critical parameters for real applications. We demonstrated a 77 K liquid nitrogen Dewar condenser as a compromised compact portable THz source unit with our fabricated QCLs. They showed a stable few ten mW peak power with sub mW average power operation. Analysis the temperature performance of structures by Non-Equilibrium Green’s Function (NEGF) method are discussed. The improvement of the active region and waveguide fabrication will also be discussed for high output power operation in order to exhibit the best performance of the compact 77 K Dewar system.

  47. Design for Stable Lasing of an Indirect Injection THz Quantum Cascade Laser Operating at Less Than 2 THz Peer-reviewed

    Tsung-Tse Lin

    International Journal of Materials Science and Applications　6　(5)　230-230　2017

    Publisher: Science Publishing Group

    DOI： 10.11648/j.ijmsa.20170605.11 　

    ISSN： 2327-2635

  48. THz quantum cascade lasers toward high output power near liquid nitrogen temperature operation with Dewar condenser

    Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz)　2016/09

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz.2016.7758681 　

  49. Recent Progress of Terahertz Quantum Cascade Lasers Peer-reviewed

    Hideki HIRAYAMA, Wataru TERASHIMA, Tsung-Tse LIN

    The Review of Laser Engineering　44　(8)　520-520　2016

    Publisher: Laser Society of Japan

    DOI： 10.2184/lsj.44.8_520 　

    ISSN： 0387-0200

    eISSN： 1349-6603

  50. Recent progress and future prospects for terahertz quantum-cascade lasers Peer-reviewed

    84　(10)　918-923　2015/10

    Publisher:

    DOI： 10.11470/oubutsu.84.10_918 　

    ISSN： 0369-8009

  51. Recent progress and future prospects of THz quantum-cascade lasers

    H. Hirayama, W. Terashima, Tsung-Tse Lin, Miho Sasaki

    Novel In-Plane Semiconductor Lasers XIV　2015/03/10

    Publisher: SPIE

    DOI： 10.1117/12.2082723 　

    ISSN： 0277-786X

  52. The 3.7THz 145K operation modulation barriers structure quantum cascade lasers

    Tsung-Tse Lin, Hideki Hirayama

    Optics InfoBase Conference Papers　2019　2015

    Publisher: OSA - The Optical Society

  53. 1.9 THz selective injection design quantum cascade laser operating at extreme higher temperature above the k B T line Peer-reviewed

    Sasaki Miho, Tsung-Tse Lin, Hideki Hirayama

    physica status solidi c　10　(11)　1448-1451　2013/11

    Publisher: Wiley

    DOI： 10.1002/pssc.201300267 　

    ISSN： 1862-6351 1610-1642

    eISSN： 1610-1642

  54. Improvement of operation temperature in GaAs/AlGaAs THz‐QCLs by utilizing high Al composition barrier Peer-reviewed

    Tsung-Tse Lin, Hideki Hirayama

    physica status solidi c　10　(11)　1430-1433　2013/11

    Publisher: Wiley

    DOI： 10.1002/pssc.201300216 　

    ISSN： 1862-6351 1610-1642

    eISSN： 1610-1642

  55. 1.9 THz indirect injection Al&lt;inf&gt;0.175&lt;/inf&gt;Ga&lt;inf&gt;0.825&lt;/inf&gt;As/GaAs quantum cascade laser operating at extreme higher temperature

    T.-T. Lin, M. Sasaki, H. Hirayama

    2013 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)　2013/09

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz.2013.6665538 　

  56. Operation temperature and T&lt;inf&gt;0&lt;/inf&gt; improvement of GaAs/AlGaAs THz QCL by utilizing higher Al composition barriers

    T.-T Lin, H. Hirayama

    2013 Conference on Lasers and Electro-Optics Pacific Rim (CLEOPR)　2013/06

    Publisher: IEEE

    DOI： 10.1109/cleopr.2013.6600250 　

  57. Threshold Current Density Reduction by Utilizing High-Al-Composition Barriers in 3.7 THz GaAs/Al$_{x}$Ga$_{1-x}$As Quantum Cascade Lasers Peer-reviewed

    Tsung-Tse Lin, Leiying Ying, Hideki Hirayama

    Applied Physics Express　5　(1)　012101-012101　2012/01

    Publisher: IOP Publishing

    DOI： 10.1143/apex.5.012101 　

    ISSN： 1882-0778

    eISSN： 1882-0786

    More details Close

    The temperature dependence of threshold current density (J_{\text{th } }) for GaAs/AlxGa1-xAs terahertz quantum cascade lasers (THz-QCLs) with different Al barrier compositions is studied. We achieved a maximum operation temperature (T_{\text{max } }) of 143 K for a 3.7 THz QCL by employing a longitudinal-optical (LO) phonon depopulation scheme. High-Al-composition barriers are used for increasing averaged LO-phonon energy. A significant reduction in J_{\text{th } } of approximately 30% was obtained by increasing the Al composition from 15 to 35%, when we used the same energy separation of the depopulation stats (E_{21}). T_{\text{max } } could be increased by using high-Al-composition structures due to the reduction of thermally-activated LO-phonon scattering.

  58. Significant reduction of threshold current density of GaAs/AlGaAs terahertz quantum cascade lasers by using high-al-content AlGaAs barrier

    Tsung-Tse Lin, Leiying Ying, Hideki Hirayama

    2011 International Conference on Infrared, Millimeter, and Terahertz Waves　2011/10

    Publisher: IEEE

    DOI： 10.1109/irmmw-thz.2011.6105198 　

  59. Thermally Activated Longitudinal Optical Phonon Scattering of a 3.8 THz GaAs Quantum Cascade Laser Peer-reviewed

    Tsung-Tse Lin, Keita Ohtani, Hideo Ohno

    Applied Physics Express　2　(2)　022102-022102　2009/01/23

    Publisher: IOP Publishing

    DOI： 10.1143/apex.2.022102 　

    ISSN： 1882-0778

    eISSN： 1882-0786

    More details Close

    Thermally activated longitudinal optical (LO) phonon scattering time ($\tau_{\text{thermal LO } }$) of excited subbands in a 3.8 THz quantum cascade laser is studied. The active region used herein is based on a LO phonon depopulation scheme. A single plasmon waveguide was used for optical confinement. By calculating the temperature dependence of threshold current density ($J_{\text{th } }$) and comparing with the experiment, $\tau_{\text{thermal LO } }$ limiting the characteristic temperature of $J_{\text{th } }$ is estimated: $\tau_{\text{thermal LO } }$ is 246 ns at 5 K, which rapidly decreases 15 ps when temperature rises up to 100 K.

Show all ︎Show first 5

Books and Other Publications 2

  1. Quantum Cascade Laser: THz QCLs Design Toward Real Applications

    Tsung-Tse Lin

    2017

    ISBN: 9789535149057

  2. Quantum Cascade Lasers (QCLs): Types and Applications

    Tsung-Tse Lin

    2016

    ISBN: 9781536103878

Presentations 64

  1. Recent Progress in Development of A UTC-PDIntegrated HEMT Photonic Double-Mixer for Beyond5G Fiber-Wireless-Convergence Network System Invited

    A. Satou, T. T. Lin, T. Otsuji

    The 12th International Symposium on Terahertz-Related Devices and Technologies: TeraTech 2025

  2. 300-GHz-Band Operation of UTC-PD-Integrated HEMT Photonic Double-Mixer

    Tsung-Tse Lin, Shota Horiuchi, Mitsuki Watanabe, Shinnosuke Uchigasaki, Koichi Tamura, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    the 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2024)　2024/09/04

  3. Verification of 300-GHz-Band Photonic Double-Mixing by UTC-PD-Integrated HEMT

    S. Horiuchi, M. Watanabe, T.-T. Lin, S. Uchigasaki, K. Tamura, T. Suemitsu, T. Otsuji, A. Satou

    the 11st International Symposium on Terahertz-Related Devices and Technology (TeraTech 2024)　2024/06/10

  4. Efficient Optical-to-sub-THz Carrier Frequency Down-Conversion by UTC-PD-Integrated HEMT

    Tsung-Tse Lin, Mitsuki Watanabe, Dai Nakajima, Keisuke Kasai, Masato Yoshida, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    2023 IEEE International Topical Meeting on Microwave Photonics (IEEE MWP 2023)　2023/10/16

  5. Utilizing High-Intensity Optical Subcarrier Signal for Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer Invited

    Tsung-Tse Lin, Dai Nakajima, Kazuki Nishimura, Mitsuki Watanabe, Keisuke Kasai, Masato Yoshida, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    The 48th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2023)

  6. テラヘルツ量子カスケードレーザーの進展 Invited

    平山 秀樹, 王 利, 林 宗澤, 陳 明曦

    第167回微小光学研究会―レーザーの新境地　2023/06/01

  7. Progressing in terahertz quantum cascade lasers: approaching room-temperature operation based on GaAs and extending to undeveloped frequencies based on GaN Invited

    Li WANG, Tsung-Tse LIN, Ming-Xi CHEN, Ke WANG, Hideki HIRAYAMA

    レーザ・量子エレクトロニクス研究会（LQE) 5月研究会　2023/05/23

  8. 高出力テラヘルツ量子カスケードレーザ Invited

    林 宗澤, 王 利, 王 科, 平山 秀樹

    レーザ・量子エレクトロニクス研究会（LQE) 5月研究会　2023/05/23

  9. Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer by High-Intensity Optical Subcarrier Signal

    Dai Nakajima, Kazuki Nishimura, Mitsuki Watanabe, Tsung-Tse Lin, Keisuke Kasai, Masato Yoshida, Tetsuya Suemitsu, Taiichi Otsuji, Akira Satou

    Optical Fiber Communication Conference (OFC 2023)

  10. 1.39-Watt Operation of THz Quantum Cascade Laser with Highly Doped Depopulation Layers

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    International semiconductor laser conference (ISLC 2022)

  11. Optical gain in terahertz quantum cascade lasers based on wide-bandgap semiconductor quantum structures ZnO/ZnMgO

    Wang Li, Lin Tsung-Tse, Grange Thomas, Wang Ke, Chen Mingxi

    The International Workshop on Nitride Semiconductors (IWN 2022)

  12. Consideration of the interface diffusions for narrow-period terahertz quantum cascade lasers

    Wang Li, Lin Tsung-Tse, Grange Thomas, Wang Ke, Hirayama Hideki

    2022 International Conference on Solid State Devices Materials (ssdm2022)

  13. Doping study of terahertz quantum cascade lasers

    Miyoshi Teppei, Wasilewski Zbig, Lin Tsung-Tse, Hirayama Hideki, Ban Dayan, Wang Kai Xi

    47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz 2022)

  14. High Doping Concentration and Variable Al Composition THz Quantum Cascade Lasers with 1.39-Watt Operation

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz 2022)

  15. Over 1 Watt THz QCLs with high doping concentration and variable Al composition in active structure Invited

    Tsung-Tse Lin

    Conference on Lasers & Electro-optics (CLEO 2022)

  16. Over 1 Watt THz QCLs with high doping concentration and variable Al composition in active structure

    Tsung-Tse Lin, Li Wang, Ke Wang, Thomas Grange, Stefan Birner, Hideki Hirayama

    27th International Semiconductor Laser Conference (ISLC 2021)

  17. Room temperature THz quantum cascade laser Invited

    Li Wang, Tsung-Tse Lin, Ke Wang, Hideki Hirayama

    The 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2021)

  18. 高出力テラヘルツQCLの進展 Invited

    林宗澤

    テラヘルツ波科学技術と産業開拓第182委員会 第45回研究会　2021/04/08

  19. Recent progress in GaAs THz-QCLs and towards realizing GaN based QCLs

    Ke Wang, Tsung-Tse Lin, Li Wang, Hideki Hirayama

    SPIE Photonics West

  20. Simulation and growth of GaN/AlGaN based terahertz quantum cascade structures

    Ke Wang, Li Wang, Tsung-Tse Lin, Koichi Fukuda, Rong Zhang, Hideki Hirayama

    The 9th Asia-Pacific Workshop on Widegap Semiconductors (APWS2019)

  21. Experimental and theoretical study of piezoelectric polarization in GaN/AlGaN terahertz quantum cascade lasers

    Li Wang, Tsung-Tse Lin, Ke Wang, Thomas Grange, Hideki Hirayama

    The 15th International Conference on Intersubband Transitions in Quantum Wells

  22. Optimization of THz QCLs by suppressing a leakage current via high energy states

    Tsung-Tse Lin, Ke Wang, Li Wang, Hideki Hirayama

    The 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2019)

  23. Recent progress of high-power THz QCLs

    Tsung-Tse Lin, Wang Ke, Wang Li, Hideki Hirayama

    理研シンポジウム第6回「光量子工学研究」

  24. Optimization of terahertz quantum cascade lasers by suppressing a carrier leakage channel via a high energy state Invited

    Tsung-Tse Lin, Hideki Hirayama

    1st International Conference on Photonics Research (ICPR2018)

  25. THz-QCLs toward high output power near liquid nitrogen temperature operation Invited

    Tsung-Tse Lin, Hideki Hirayama

    14th International Conference on Modern Materials and Technologies (CIMTEC2018)

  26. Recent progress of high power THz quantum cascade lasers Invited

    Tsung-Tse Lin

    Nanotech Malaysia 2018

  27. Recent progress and future prospects of THz quantum cascade lasers Invited

    Tsung-Tse Lin

    國立交通大学特別講演　2017/12/25

  28. 間接注入機構を用いたTHz QCL高温動作の進展

    Tsung-Tse Lin, Wang Ke, Wang Li, Koichi Fukuda, Hideki Hirayama

    理研シンポジウム第5回「光量子工学研究」

  29. Design of THz QCLs toward high output power near liquid nitrogen temperature operation Invited

    Tsung-Tse Lin, Hideki Hirayama

    Nano Science & Technology-2017 (Nano S&T 2017)

  30. Design THz quantum cascade lasers toward high output power near liquid nitrogen temperature operation

    Tsung-Tse Lin, Hideki Hirayama

    International Conference on Solid State Devices and Materials (SSDM 2017)

  31. waveguide design for GaN/AlGaN terahertz quantum cascade lasers

    Ke Wang, Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    The 14th International Conference on Intersubband Transitions in Quantum Wells (ITQW2017)

  32. THz quantum cascade lasers toward high output power near liquid nitrogen temperature operation

    Tsung-Tse Lin, Hideki Hirayama

    The 14th International Conference on Intersubband Transitions in Quantum Wells (ITQW2017)

  33. THz quantum cascade lasers toward high output power near liquid nitrogen temperature operation

    Tsung-Tse Lin, Hideki Hirayama

    The 24th Congress of the International Commission for Optics (ICO-24)

  34. THz quantum cascade lasers toward high output power near liquid nitrogen temperature operation with Dewar condenser

    Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    The 44th International Symposium on Compound Semiconductors (ISCS 2017)

  35. Variable height active structure design THz QCLs operating at 3.7 THz with the maximum operation temperature 145 K

    Tsung-Tse Lin and Hideki Hirayama

    The 44th International Symposium on Compound Semiconductors (ISCS 2017)

  36. Design of indirect injection scheme THz QCLs with high operation temperature

    Tsung-Tse Lin, Hideki Hirayama

    The 44th International Symposium on Compound Semiconductors (ISCS 2017)

  37. Recent progress of GaN-based terahertz quantum cascade lasers Invited

    Wataru Terashima, Tsung-Tse Lin, Hideki Hirayama

    5th Russia-Japan-USA-Europe Symposium on Fundamental & Applied Problems of Terahertz Devices & Technologies (RJUSE TeraTech-2016)

  38. Hz quantum cascade lasers toward high output power near liquid nitrogen temperature operation with Dewar condenser

    Tsung-Tse Lin, Wataru Terashima, Hideki Hirayama

    The 41st International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2016)

  39. Progress of THz quantum cascade lasers using nitride semiconductor Invited

    Hideki Hirayama, Wataru Terashima, Tsung-Tse Lin, Shiro Toyoda, Norihiko Kamata

    74th Device Research Conference (DRC 2016)

  40. Modulation active structure design indirect injection scheme THz QCLs Invited

    Tsung-Tse Lin, Hideki Hirayama

    EMN meeting on terahertz

  41. Indirect injection scheme THz QCLs with high operation temperature Invited

    Tsung-Tse Lin, Hideki Hirayama

    EMN meeting on Vacuum Electronics

  42. 間接注入機構を用いたTHz QCL高温動作の進展

    林宗澤, 平山秀樹

    理研シンポジ ウム第3回「光量子工学研究」

  43. Modulation barrier design AlxGa1-xAs/GaAs terahertz quantum cascade lasers

    Tsung-Tse Lin, Hideki Hirayama

    The 13th International Conference on Intersubband Transitions in Quantum Wells (ITQW2015)

  44. AlGaAs/GaAs quantum cascade lasers with modulation Al composition barriers design lasing at 3.7 THz, 145 K

    Tsung-Tse Lin, Hideki Hirayama

    The Second International Symposium on Frontiers in THz Technology (FTT 2015)

  45. AlGaAs/GaAs quantum cascade lasers with variable Al composition barriers lasing at 3.7 THz

    Tsung-Tse Lin, Hideki Hirayama

    International Quantum Cascade Lasers School & Workshop 2014 (IQCLSW 2014)

  46. テラヘルツ量子カスケードレーザの現状と今後の展望 Invited

    平山秀樹, 寺嶋亘, 林宗澤, 佐々木美穂

    テラテクビジネスセミナー「産業応用拡大に向けたテラヘルツ技術の最先端と展望」　2014/09/05

  47. テラヘルツ量子カスケードレーザの進展と今後の展望 Invited

    平山秀樹, 寺嶋亘, 林宗澤, 佐々木美穂

    テラヘルツ波科学技術と産業開拓第182委員会、第21回研究会　2014/07/17

  48. 1.9 THz indirect injection Al0.175Ga0.825As/GaAs quantum cascade laser operating at extreme higher temperature

    Tsung-Tse Lin, Miho Sasaki, Hideki Hirayama

    The 38rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2013)

  49. Operation temperature and T0 improvement of GaAs/AlGaAs THz QCL by utilizing higher Al composition barriers

    Tsung-Tse Lin, Hideki Hirayama

    10th Conference on Lasers and Electro-Optics Pacific Rim 2013 (CLEO-PR 2013)

  50. Improvement of operation temperature with lager T0 in AlGaAs THz QCLs by utilizing high Al composition

    Tsung-Tse Lin, Hideki Hirayama

    The 40th International Symposium on Compound Semiconductors (ISCS 2013)

  51. High Al composition AlGaAs THz QCLs with operation temperature and T0 improvement

    Tsung-Tse Lin, Hideki Hirayama

    Advance Lasers and Photon Sources 2013 (ALPS’ 2013)

  52. Development of Deep-UV LEDs and THz-QCLs and those applications Invited

    Hideki Hirayama, Sachie Fujikawa, Noritoshi Maeda, Wataru Terashima, Tuung-Tse Lin, Norihiko Kamata

    Advance Lasers and Photon Sources 2013 (ALPS’ 2013)

  53. High-Al-composition GaAs/AlxGa1-xAs terahertz quantum cascade lasers for higher temperature operation

    Tsung-Tse Lin, Hideki Hirayama

    31th International Conference on the Physics of Semiconductors (ICPS2012)

  54. Higher temperature operation LO phonon depopulation terahertz quantum cascade lasers design with high-Al-composition

    Tsung-Tse Lin and Hideki Hirayama

    International Conference on Superlattices, Nanostructure, and Nanodevices (ICSNN2012)

  55. テラヘルツ量子カスケードレーザーの進展と今後の展望 Invited

    平山秀樹, 寺嶋亘, 林宗澤

    レーザー学会学術講演会第32回年次大会　2012/01/31

  56. Recent progress and future prospects of THz-quantum-cascade lasers Invited

    Hideki Hirayama, Wataru Terashima and Tsung-Tse Lin

  57. テラヘルツ量子カスケードレーザーの進展と今後の展望 Invited

    電子情報通信学会・エレクトロニクスソサエティ・電子デバイス研究会「ミリ波・テラヘルツ波デバイス・システム」　2011/12/14

  58. Proposal of utilizing high-Al-composition AlxGa1-xAs / AlyGa1-yAs terahertz quantum cascade lasers

    Tsung-Tse Lin, Hideki Hirayama

    The 1st International Symposium on Terahertz Nanoscience (TeraNano 2011) and 2nd Workshop of International Terahertz Research Network (GDR-I THz 2011)

  59. Significant reduction of threshold current density of GaAs/AlGaAs terahertz quantum cascade lasers by using high-Al-content AlGaAs barrier

    Tsung-Tse Lin, Leiying Ying, Hideki Hirayama

    The 36rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2011)

  60. Temperature dependence of threshold current density of GaAs/ AlxGa1-xAs terahertz quantum cascade lasers with different Al composition

    Tsung-Tse Lin, Leiying Ying, Hideki Hirayama

    The 11th International Conference on Intersubband Transitions in Quantum Wells (ITQW2011)

  61. Fabrication of copper metal-metal waveguide by radio frequency sputtering method

    Keita Ohtani, Tsung-Tse Lin, Hideo Ohno

    The 10th International Conference on Intersubband Transitions in Quantum Wells (ITQW2009)

  62. Fabrication and operation of a metal-metal waveguide GaAs terahertz quantum cascade laser

    Tsung-Tse Lin, Keita Ohtani, Hideo Ohno

    14th International Conference on Modulated Semiconductor structures (MSS-14)

  63. Temperature dependence of threshold current density of terahertz QCL

    Tsung-Tse Lin, Keita Ohtani, Hideo Ohno

    2008 International Conference on Solid State Devices and Materials

  64. Temperature dependence of threshold current density of terahertz QCL: Comparison with mid-infrared QCL

    Tsung-Tse Lin, Keita Ohtani, Hideo Ohno

    International Quantum Cascade Lasers School & Workshop

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Industrial Property Rights 6

  1. 量子カスケードレーザー素子（面発光）

    Joosun Yun, 林宗澤, 平山秀樹

    Property Type: Patent

  2. 量子カスケードレーザー素子（フォトニック結晶）

    陳 明曦、王 利、林 宗澤、大谷 知行、平山 秀樹

    Property Type: Patent

  3. 量子カスケードレーザー素子（室温動作テラヘルツ量子カスケードレーザー）

    王利、林宗澤、平山秀樹

    Property Type: Patent

  4. 量子カスケードレーザー素子（水平リーク電流低減により高出力THz-QCLを実現する提案）

    平山秀樹, 林宗澤, 王利, 王科

    Property Type: Patent

  5. 量子カスケードレーザー素子（間接注入型機構による低周波数、高温動作THz-QCLの実現）

    平山秀樹、林宗澤、佐々木美穂

    Property Type: Patent

  6. 量子カスケードレーザー素子（高Al組成AlGaAsバリアを用いた高温型THz-QCLの提案）

    平山秀樹, 林宗澤

    Property Type: Patent

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Research Projects 6

  1. A Study on realizing unexplored frequency and room temperature operation THz-QCL through innovation of inter-subband transition mechanism

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (S)

    Institution: Institute of Physical and Chemical Research

    2024/04/01 - 2029/03/31

  2. Research on high output and control of metamaterial THz QCLs

    Lin Tsung-Tse

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    Category: Grant-in-Aid for Scientific Research (C)

    Institution: Institute of Physical and Chemical Research

    2018/04 - 2021/03

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    In this study, the origin of the new leak current in THz QCL is clarified via the operated energy levels and high energy subband levels. It is analyzed by the first-principles calculation based on the non-equilibrium green's function (NEGF) method. We focus on the optimization of the active structure and reducing the leak current via high energy levels with large injection current. It is the first proposal to develop a variable Al composition barrier-well active structure THz QCL in order to obtains high operation temperatures and large optical gain. The metal surface pattern is also analysis by FDTD and 3D-CWT method for the surface emission THz QCL. We have achieved a 1.3 W peak output and an average output of 55 mW QCL at 4.1 THz.

  3. Fabrication process of double metal waveguide structures for higher temperature operation of GaN-based THz-QCLs

    Terashima Wataru, Lin Tsung-Tse

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Exploratory Research

    Institution: Institute of Physical and Chemical Research

    2015/04/01 - 2017/03/31

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    A fabrication process of double metal waveguide structures on gallium-nitride materials and a design of functionalizing quantum cascade structures on gallium-arsenide materials are investigated for the purpose of higher temperature operation of terahertz quantum cascade lasers. High temperature operation up to 145 K is realized by incorporating a modulation- and an electron-barrier extraction layers to quantum cascade structures on gallium-arsenide materials. On the establishment of the fabrication process for double metal waveguide structures on gallium-nitride materials, the lift-off of gallium-nitride quantum structures from sapphire substrates is realized by optimizing metal bonding conditions and applying laser ablation.

  4. Studies of high temperature operation THz QCLs by modulation barriers structure

    Lin Tsung-Tse

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

    Category: Grant-in-Aid for Young Scientists (B)

    Institution: Institute of Physical and Chemical Research

    2015/04 - 2017/03

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    Here we utilize the modulation barriers active region designe with different barriers and wells height at one period of THz QCLs. In order to realize the difficult alternative consideration of barriers height at injection/extraction and emission layers. The wide-low barriers at emission layers reduce the non-radiative interface roughness (IR) scattering and keep the high optical gain. And the thin-high barriers improve the injection/extraction efficiency by the same IR scattering at injection/extraction layers. We demonstrate the first experimental results of high temperature operation THz QCLs designed by this kind of variable height structure. We also report the high output power THz QCLs with peak power 250 mW and average power 2.2 mW at low temperature; fabricate the compact potable 77K liquid nitrogen temperature Dewar condenser by THz QCLs with peak power 10 mW and average power 0.1 mW.

  5. THz量子カスケードレーザの動作高温化と周波数拡大に関する研究

    平山 秀樹

    System: 産学が連携した研究開発成果の展開 研究成果展開事業 産学共創基礎基盤研究プログラム

    Institution: 独立行政法人理化学研究所

    2011 - 2015

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    テラヘルツ量子カスケードレーザ(THz-QCL)は、小型・高効率、長寿命、連続出力、安価なテラヘルツ光源として、各種透視検査・計測機器など幅広い応用分野での利用が期待されています。本研究では、THz-QCLに新しい量子構造や新規半導体材料系を導入するなど素子構造を革新することで、動作温度の向上、周波数領域の拡大、閾値電流の低減などの高性能化を行い、実用化を目指したTHz-QCLの開発を行います。

  6. Control of carrier dimensionality in InAs quantum cascade lasers and its effect on laser characteristics

    OHNO Hideo, OHTANI Keita, LIN Tsung-tse, BELMOUBARIK Mohamed, SATO Hiroki

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (A)

    Institution: Tohoku University

    2007 - 2009

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    To investigate the effect of carrier dimensionality on the laser characteristics of InAs quantum cascade lasers (QCLs), we applied the magnetic field in the direction parallel and perpendicular to quantum wells (QWs) layers and measured the emission properties. When the magnetic field in the direction perpendicular to QWs was increased, the threshold current density (J_<th>) was decreased most probably due to the formation of the Landau levels. On the other hand, when the magnetic field parallel to QWs was increased, the enhancement of the slope efficiency was observed whereas J_<th> remained unchanged. Also to study its effect on the characteristics of terahertz (THz) QCLs, we fabricated the GaAs THz QCLs. In addition, we observed the intersubband transitions in ZnO QWs which is expected to improve the temperature characteristics of THz QCLs.

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