Ultrafast cross-well carrier transport in a strained multiple-quantum-well InGaAs-GaAs p-i-n modulator

We report ultrafast optical pump-probe measurements of cross-well carrier transport in a strained multiple-quantum-well InGaAs-GaAs p-i-n modulator. The transmission response of the modulator is recorded over a range of reverse bias values, wavelengths, and power levels, producing several qualitatively different response types. A simplified physical model is developed to describe this behavior. This model includes transmission changes due to exciton saturation and excitonic field screening, carrier emission from the quantum wells and drift through the intrinsic region, and voltage diffusion across the p- and n-doped electrodes. This model agrees well with the experimental data.