A New Optical Gain Model for Quantum Wells Based on Quantum Well Transmission Line Modeling Method

This paper presents a new method for modeling the gain spectrum in quantum well (QW) structures based on the QW transmission line modeling (QW-TLM) method. In the QW-TLM method, three parallel RLC filters together with their associated weight coefficients constitute a QW-TLM unit, which represents the processes that electrons transit from the conduction band to the heavy hole band, the light hole band, and the spin-orbit split-off band at a specific wave vector. Parallel QW-TLM units are adopted to describe the electron transitions in the wave vector space. Furthermore, the optical gain model of QWs based on the QW-TLM method is presented. The gain spectrum obtained through the QW-TLM method is agreeable with the gain spectrum calculated from the analytical expression in a large wavelength range from 1300 to 1700 nm. In order to reduce the computation time, under sampling QW-TLM is proposed to model the gain curve of QWs. The simulation result shows that the gain curve obtained from under sampling QW-TLM is consistent with the gain curve obtained through the theoretical derivation from 1510 to 1575 nm, which satisfies the requirement of studying the dynamic spectral characteristics of QW devices.