Abstract

Current induced switching of the lasing transition from 912 nm (n=2, QW) to 884 nm (barrier) has been observed in lossy gain-guided strained-layer InGaAs/GaAs single-quantum-well (QW) laser stripes. The QW structure, consisting of an undoped InGaAs active layer sandwiched between undoped GaAs layers in a separate confinement structure, was prepared by molecular beam epitaxy (MBE). The constraints on well depth and thickness in a strained layer system coupled with higher lateral mode losses provide for dominant recombination from the barriers, due to excessive carrier spillover at higher injection levels. Investigations on the time-averaged pulsed emission spectra over a 40 nm wavelength range and a current range covering both QW and barrier transitions show the presence of a broad gain spectrum at the higher injection levels that could, in principle, be used to generate very short pulses by using standard mode-locking techniques in addition to use in applications that require wavelength switching. The change in gain with drive current was seen to be fairly high at the gain peak of the shorter lasing region, whereas strong gain saturation effects were observed at the longer wavelength, resulting in spectral hole burning at high currents.

© 1992 Optical Society of America