Picosecond time-resolved measurements of electroabsorption in an InGaAs/GaAs multiple quantum well p-i-n modulator

We report the first picosecond time-resolved measurements of electroabsorption in a strained InGaAs/GaAs multiple quantum well p-i-n structure as a function of applied bias at various optical excitation densities. The data above 4 V are explained by a model which assumes a rise time dominated by a single carrier sweep-out time and a decay dominated by lateral diffusion. A bias independent electro-absorption rise time of 10±2 ps is obtained and appears to be limited by the transit time of carriers across the structure. The decay time is also ≊10 ps. Below 4 V the decay time increased to 80 ps as the bias was reduced to 0 V. This increase may be related to the change in depletion length with bias in the intrinsic region.