Abstract

Laser amplifiers with two or more electrodes have recently been studied for potential applications as wavelength converters [1], tunable filters [2], and all-optical switches [3]. The conventional understanding of switching in a two-section amplifier is associated with the saturation of interband absorption in the unpumped (sometimes relatively lightly pumped) section when the input optical signal exceeds a certain critical level. However, in such a device, in the absence of AR-coating, and with the non-absorbing section driven close to threshold, there is the potential for a much more complicated interplay of physical mechanisms for nonlinearity. In particular, gain saturation and nonlinear refraction can play important roles in addition to the saturable absorption already mentioned, and the device behaviour will incorporate a rich variety of effects. Experimental studies of split-contact amplifiers have revealed many interesting switching characteristics [4,5,6] which have yet to be quantified theoretically.

© 1992 Optical Society of America