Impedance, modulation response, and equivalent circuit of ultra-high-speed InGaAs/GaAs MQW lasers

We present the first direct on-wafer measurements of the electrical impedance of p-doped In0.35Ga0.65As/GaAs MQW lasers, and use the results to derive an equivalent circuit model for frequencies up to 50 GHz. In order to explain the impedance characteristics, the effects, the effects of carrier capture into the QWs as well as the space-charge capacitance of the diode junction must be taken into account. Utilizing this equivalent circuit in conjunction with intrinsic laser parameters derived from RIN measurements, the electrical modulation response curves can be fitted accurately up to 40 GHz