Abstract

For future high-speed optoelectronic systems, it is Important to investigate ultrafast phenomena in semiconductor lasers, such as short-pulse generation and ultrahigh-speed modulation. It has been recently demonstrated that quantum well (QW) lasers have an advantage in generating shorter light pulses, because the differential gain is enhanced by a factor of 4 compared with conventional double-heterostructure lasers."' In fact, an extremely narrow light pulse (<1.3 ps) was successfully observed in a quantum well laser.² However, spectral dynamics of semiconductor lasers in the picosecond time domain have not been sufficiently studied. We investigate temporal spectral dynamics of gain-switched QW lasers having various QW structures. Results indicate that the spectral dynamics depend strongly on the number of QWs even in the same excitation conditions. This is the result of the difference in carrier density (cm⁻²) formed in each well.

© 1989 Optical Society of America