Terahertz Quantum Device Research Team

Team Leader

Hideki Hirayama


Hideki Hirayama


Access map

hirayama [at] riken.jp

Terahertz Quantum Device Research Team,
RIKEN Center for Advanced Photonics

#W526 5F Cooperation Center,
2-1 Hirosawa, Wako, Saitama 351-0198 Japan

TEL: +81-(0)48-467-9389
FAX: +81-(0)48-462-4647

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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.


Optical Devise Engineering, Quantum Electronics, Semiconductor Physics


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


  1. Development of low-frequency THz-QCLs by introducing novel quantum structures
  2. Development toward room temperature operation of THz-QCLs
  3. Research toward realizing unexplored-frequency QCL using nitride semiconductors

Schematic structure and operating properties of terahertz quantum-cascade laser (THz-QCL)

Selected Publications

  1. Wang, L., Lin, T., Wang, K., and Hirayama, H.: “Parasitic transport paths in two-well scattering-assisted terahertz quantum cascade lasers”, Applied Physics Express, Vol. 12, No. 8, pp. 082003-1-5 (2019).
  2. Lin, T., Wang, L., Wang, K., Grange T. and Hirayama, H.: “Optimization of terahertz quantum cascade lasers by suppressing carrier leakage channel via high-energy state”, Appl. Phys. Express, vol. 11, No. 11, 112702 1-5 (2018).
  3. Wang, K., Grange, T., Lin, T., Wang, L., Jehn, Z., Birner, S., Yun, J., Terashima, W. and Hirayama, H.: “Broading mechanisms and self-consistent gain calculation for GaN quantum cascade laser structures”, Appl. Phys. Lett., vol. 113, No. 6, 061109 1-5 (2018).
  4. Wang, K., Lin, T., Wang, L., Terashima, W. and Hirayama, H.: “Controlling loss of waveguides for potential GaN terahertz quantum cascade lasers by tuning the plasma frequency of doped layers”, Jap. J. Appl. Phys. Vol. 57, No. 8, 081001 1-5 (2018).
  5. Lin, T. and Hirayama, H.: “Variable barrier height AlGaAs/GaAs quantum cascade laser operating at 3.7 THz”, physica status solidi (a), Vol. 125, pp. 1700424 (2017).


Hideki HirayamaTeam Leader
Tsung Tse LinResearch Scientist
Masafumi JoSenior Research Scientist
Li WangPostdoctoral Researcher
Muhammad Ajmal KhanSpecial Postdoctoral Researcher
Sachie FujikawaVisiting Scientist
Ke WangVisiting Scientist