Effect of device parameters on gain switching in quantum cascade lasers

Abstract

This letter reports the theoretical analysis on the effect of device parameters on optical pulse characteristics for gain switching in quantum cascade lasers (QCLs). A 9 µm QCL consisting of 48 periods of injector and active regions is considered in this work. The device is excited using square electrical pulses and the effect of the spontaneous emission factor, mirror reflectivity and the optical confinement factor on short pulse generation is studied. Also, the optimum pulse characteristics under each condition are analyzed in detail. It is observed that, for a mirror reflectivity of 0.25, optical pulses with at least a full width half maximum (FWHM) of 10.03 ps with a peak power of 60.2 mW are obtained. Further, optical pulses with an FWHM of 10.11 ps and 56.45 ps are obtained at lower drive currents at an optical confinement factor of 0.35.