Abstract

Carrier dynamic processes in semiconductor lasers, such as spectral holeburning and dynamic carrier heating, give rise to nonlinear gain. This affects many of the important static and dynamic laser characteristics, including the bandwidth and damping of high speed lasers. Recent time-domain pump-probe experiments1 have shown that several ultrafast processes contribute to nonlinear gain in InGaAs/InGaAsP laser structures with time-constants varying from sub-100fs to 1ps, but these are not yet fully understood. Here we describe measurements of ultrafast carrier dynamic processes in InGaAs/InGaAsP laser amplifiers using the technique of highly non-degenerate four-wave mixing²,³ (FWM), with pump-probe detunings of >1THz capable of measuring effects with time-constants of <200fs. We have used the technique to make quantitative measurements of both the time-constants and nonlinear gain parameters for the dominant processes.

© 1993 Optical Society of America