Abstract

A number of physical systems exhibit hysteresis and bistability, ranging from electronic devices like a Schmitt trigger, to quantum devices like the single-atom micromaser. Lasers, and laser diode amplifiers (LDA) have been demonstrated to exhibit dynamical hysteresis, and the intimate connection between this bistability and delayed bifurcations has been theoretically and experimentally elucidated. Bistability and hysteresis in LDAs is especially interesting for its potential application in developing optical switches and logic gates. For LDAs, Roy and coworkers¹ have demonstrated that the width of the hysteresis loop in the output of the amplifier, when an input signal is periodically modulated, increases with an increase in the frequency of modulation. These workers derived scaling laws for the width of the hysteresis versus frequency, for different bias conditions of the amplifier. Most previous experiments that examined hysteresis in amplifiers utilised the amplifier in a transmission mode, where the light transmitted through the amplifier was monitored. Reflection mode operation of diode laser amplifiers has not been as thoroughly investigated, though it is expected to be of relevance to some forms of logic gates, such as NAND and NOR gates.

© 1996 Optical Society of America