Simulations and measurements of the frequency response of asymmetric multiple quantum well lasers

A detailed rate equation model to simulate the steady state and frequency response characteristics of asymmetric multiple quantum well (AMQW) lasers was discussed in this thesis. Model parameters were determined by fitting to measurements of the transition cavity length (TCL). Simulations of mirror image AMQW lasers demonstrated the capability of calculating the carrier distribution, TCL, total gain and LI curves. The occurrence of simultaneous lasing at several wavelengths demonstrated that for AMQW lasers the gain from different quantum wells is essentially inhomogeneously broadened. It was found that numerical solutions of the rate equations may be necessary for predicting the frequency response of AMQW lasers. However, an analytic approximation for the resonance frequency was derived that produced values similar to those obtained using numerical methods.; The effective resonance frequency trends with current and temperature derived from measurements of the frequency response showed no significant difference for several mirror image structures. These results indicate that there is little effect of well position and carrier transport on the resonance frequency of these structures. Measurements of the output power and frequency response were also carried out as the wavelength was tuned using an external cavity. The trends derived from these measurements demonstrated that the wavelength dependence of the resonance frequency was similar to that of the laser output power. The trends observed here support the analytic equation for the resonance frequency of AMQW lasers, which is dependent on the photon density and independent of well position and carrier transport times. Simulations of the resonance frequency as a function of current, temperature and wavelength using the rate equation model gave results that agreed with these measurements.