Bifurcation connection between external cavity modes in a semiconductor laser exhibiting low frequency fluctuations

Summary form only given. Semiconductor lasers subject to delayed optical feedback from external reflectors and operating close to threshold exhibit complex output oscillations characterized by sudden intensity drops (low frequency fluctuations or LFF). LFF is often described as a dynamical regime consisting of many unstable external cavity modes (ECMs). But recent experimental and numerical studies suggest that LFF may already appear for a low number of ECMs. As the feedback rate increases from zero, each ECM sequentially appears, undergoes a Hopf bifurcation followed by more complicated bifurcations until transient or sustained LFF is observed. Using a new continuation method specially designed for delay-differential equations, we have found that successive ECMs are connected by closed branches of periodic solutions.