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Outline

Terahertz light having both the transparency of radio wave and the high resolution of light is expected to be used in a wide range of application fields as a light source for various perspective and nondestructive inspections. We are developing THz-QCL (terahertz quantum-cascade laser), which is expected to be a very compact, portable, high power terahertz light source. Through the introduction of a new quantum subband structure and/or nitride semiconductors, THz-QCL aiming for implementation in society is being developed by performing room temperature oscillation and enlarging the operating frequency region which have been impossible so far. By developing the next generation compact terahertz imaging devices, we would like to contribute to the realization of a prosperous society in the near future.

Fields

Optical Devise Engineering, Quantum Electronics, Semiconductor Physics

Keywords

Terahertz, Quantum cascade lasers, Inter-subband transition, Nitride semiconductors lasers, Molecular-beam epitaxy

Subjects

1. Development toward room temperature operation of THz-QCLs
2. Development of watt-class high-power THz-QCLs
3. Development of unexplored-frequency QCL using nitride and oxide semiconductors
4. Development of surface emitting THz-QCL
5. Development of mobile THz-QCL light source for nondestructive inspection

Selected Publications

1. Wang, L., Lin, T. T., Wang, K., and Hirayama, H.: “Clean three-level direct-phonon injection terahertz quantum cascade laser” , Applied Physics Letters, Vol. 122, pp. 221103 (2023).
2. Lin, T. T., Wang, L., Wang, K., Grange, T., Birner, S., Miyoshi, T., and Hirayama, H.:” Increasing the output power of a heavily doped terahertz quantum cascade laser by avoiding the subband misalignment” , Journal of Applied Physics, Vol. 132, pp. 173101-1-10 (2022).
3. Lin, T. T., Wang, L., Wang, K., Grange, T., Birner, S., and Hirayama, H.:” Over one watt output power terahertz quantum cascade lasers by using high doping concentration and variable barrier-well height” , physica status solidi RRL, Vol. 16, pp. 2200033 (2022).
4. Wang, L., Lin, T. T., Wang, K., and Hirayama, H.: “Non-relevant quantum levels effecting on the current in 2‑well terahertz quantum cascade lasers” , Scientific Reports, Vol. 12, 17378 (2022).
5. Wang, L., Lin, T. T., Wang, K., and Hirayama, H.: “Limitation of parasitic absorption in designs of three-state terahertz quantum cascade lasers with direct-phonon injection” , Applied Physics Express, Vol. 15, pp. 052002 (2022).

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