Abstract

The riddle of low frequency fluctuations (LFF) in external cavity semiconductor lasers has been present for more than twenty years, yet the complexities of its origins have been slow to unravel. These fluctuations are characterised by a sharp drop in power followed by a gradual stepping recovery to the initial level. The severity of the intensity drop off during a LFF will certainly lead to deleterious consequences in applications where stability is a crucial factor. The conventional scenario has only recently been explained as essentially a noise induced process, triggered when the system comes too close to an unstable mode as it progresses through a series of attractor ruins centred on stable external cavity modes, each with a higher gain than the preceding one [1]. The time series and the power spectra show that the drop-offs are composed of very short pulses [2].

© 1998 IEEE