Impedance, modulation response, and equivalent circuit of ultra-high-speed In0.35Ga0.65As/MQW lasers with p-doping

On-wafer measurements of the frequency-dependent impedance, modulation response, and RIN power spectra of ultra-high-speed p-doped In0.35Ga0.65As/GaAs MQW lasers are presented and analyzed. The experimental results are shown to be accurately modeled by an equivalent circuit which accounts for both the carrier transport/capture dynamics and the junction space-charge capacitane. We find that the carrier escape time out of the QW's in our laser structure is much larger than the carrier capture time, and therefore the interplay between carrier capture and re-emission is not affecting the high-speed modulation dynamics. On the other hand, the absolute values of both the carrier capture time and the space-charge capacitane still limit the modulation bandwidth