Characteristics of Cavity Round-Trip Time Pulses in Short-Cavity Q-Switched AlGaAs Multiple-Quantum-Well Semiconductor Lasers

Abstract
In the AlGaAs/GaAs two-section multiple-quantum-well (MQW) laser system, Q-switched optical pulses whose width is shorter than the cavity round-trip time were obtained by driving the gain section with 200 ps electrical pulses. The pulse-width characteristics were measured while varying the cavity length, and the optimum cavity length for obtaining the shortest optical pulse was found. When the cavity length was 170–200 µm, the shortest optical pulse with a width of 6–8 ps was obtained. We also found a profile change in the second-harmonic-generation (SHG) auto-correlation trace when the cavity length was changed.