Modeling multiple-longitudinal-mode dynamics in semiconductor lasers

We present a time-dependent coupled-wave equation analysis for simulating both single- and multilongitudinal-mode dynamics in semiconductor lasers, while incorporating frequency-dependent gain in a particularly simple way. In our first application, we analyze the response of Fabry-Perot semiconductor lasers to feedback levels ranging from -60 to -30 dB. This allows us to anchor, continuously, from single-mode phenomena at weak feedback levels to multimode behavior at stronger feedback levels. To our knowledge, this is the first simulation of multilongitudinal-mode dynamics that are induced in a laser at feedback levels exceeding -30 dB, Feedback-induced phenomena provide a significant test of both the single-mode and multimode capabilities of our coupled-wave model. In our second application, we analyze a modern, large-scale device for which multiple longitudinal modes, as well as compound cavity modes, are a significant possibility. Specifically, we consider facet-coating requirements for a new class of monolithic master-oscillator power-amplifier (MOPA) devices.