Y. Sakasegawa,1* N. Sekine1, S. Saito1, A. Kasamatsu1, I. Hosako1, M. Ashida2
1National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795, Japan
2Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 Osaka, Japan
Nano-Micro Conference, 2017, 1, 01010
Published Online: 06 October 2017 (Abstract)
Terahertz quantum cascade lasers (THz-QCLs) have attracted much attention as possible carrier sources for ultra high-speed wireless communications in the future, which owes to their high output powers and the absence of relaxation oscillations in QCLs. We have recently reported a photogenerated carrier-based optical-to-THz modulation scheme for THz-QCLs . In the presentation, the intensity and spectral changes in THz-QCLs induced by photo-injected carriers at low temperature will be discussed together with the relevant relaxation mechanisms for the injected carriers. Furthermore, to obtain a quantitative understanding of the rich phenomena by the optical injection, we developed a global simulation scheme applicable to a wide variety of optical excitation experiments on QCLs including strong excitation densities (Figure 1) . With the most of internal parameters, e.g., electron temperatures, scattering times, gains, and waveguide loss, treated as spatiotemporal and carrier density-dependent, the rate equation was solved to obtain the number of photon in the cavity. The output power (converted from the number of photons using the time-varying reflectivity at the cavity facet) well reproduces the experimental results.
Figure 1. Model grid for the analysis of the optically excited QCL.
N.S. acknowledges funding by Collaborative Research Based on Industrial Demand of the Japan Science and Technology Agency.
 Y. Sakasegawa; S. Saito; N. Sekine; A. Kasamatsu; M. Ashida; I. Hosako, Japanese Journal of Applied Physics. 55, 102701 (2016). doi:10.7567/JJAP.55.102701
 Y. Sakasegawa, N. Sekine, S. Saito, A. Kasamatsu, M. Ashida, and I. Hosako, Journal of Computational Electronics. 16, 382 (2017). doi:10.1007/s10825-017-0962-2
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