Time-dependent semiclassical theory of gain-coupled distributed feedback lasers

A semiclassical treatment of the time-dependent behavior of a gain-coupled, distributed feedback laser (DFL) has been developed. This treatment takes into account the field propagation within the DFL, and is therefore capable of predicting its behavior even for extremely short pump pulses. Comparisons are made to existing steady-state and transient theories where they are valid, showing good agreement, and new predictions are made of the behavior in the short pump pulse regime. It is found that the emitted pulse duration is dominated by the transit time through the pumped region. By studying the evolution of the field distribution inside the cavity, insight can be gained into the operation of the DFL. The effect of spatial hole burning in a gain-coupled DFL is treated and found to be small.