Optical spectra simulation for terahertz quantum cascade lasers based on a circuit-level model

摘要

In this paper, a novel equivalent circuit model of terahertz quantum cascade lasers (THz QCLs) is introduced by virtue of revised three level multi-mode rate equations. This model accounts for influence of multi-mode on steady and optical spectra characteristics of THz QCLs. Both the photon gain coefficient and the spontaneous emission coupling coefficient depend on the wavelength in this model. The nonradiative scattering times, radiative spontaneous relaxation time and electron escape time are obtained by a self-consistent scheme. The model enables the analysis of the steady and optical spectra characteristics of THz QCL using general circuit analysis software, which overcomes the shortcomings of complex and long simulation time of numerical analysis method. Based on this novel model, the optical spectra characteristics as well as the optical power and bias voltage versus input current curves of a 2.4THz device with lattice temperature at 5K and 78K are investigated by using a circuit simulator (PSPICE). Results indicate that the model is practical and accurate for THz QCL simulation studying.