Design and simulation of three wavelength terahertz GaN quantum cascade laser

Quantum cascade laser (QCL) is a promising candidate for comparatively less developed terahertz spectral range. GaN based QCLs provide significant advantages over traditional GaAs based QCLs due to their higher LO phonon energy. Multiple wavelength hetero active region cavity offers various advantages like multiple emission wavelength for spectroscopy, nonlinear optical phenomena, and second harmonic generation. In this paper, we propose and design a multiple wavelength hetero cavity terahertz GaN based QCL emitting at 1.7 THz, 4.3 THz, and 7.2 THz. We present detail modeling of the system and final gain spectrum. We observe high gain (~ 250 cm^-1) with multiple wavelength output emission. We also observe the sensitivity of the emission on temperature and find that the gain decreases sharply with increase in the temperature.