Broadband tunable picosecond semiconductor lasers

Intense photoexcitation of GaAs by picosecond laser pulses creates a superdense electron-hole plasma (∼1020 cm−3) which sustains laser action from 8900 Å in the IR to 7700 Å in the visible. Tunable picosecond laser pulses are obtained by moving a slightly wedged ultrashort cavity in the focus of the pump laser pulse.