Ultrafast recovery time in a strained InGaAs-AlAs p-i-n modulator

We have performed sub-picosecond resolution measurements of the optical recovery of InGaAs-AlAs multiple quantum well p-i-n structures that exhibit strong excitonic features, a clear quantum confined Stark effect and low photocurrent. The recovery times, measured as a function of applied electrical bias and optical excitation density, are much shorter than that predicted by carrier thermionic emission rates from the quantum wells. An observed ultrafast recovery time of 28 ps makes this material system promising as a fast modulator with low thermal dissipation or as a saturable absorber for semiconductor and fiber laser mode locking.<>