Semiconductor laser device modeling

The semiconductor laser offers enormous advantages as a practical device in many technological applications because of its very large gain per unit length. This translates into compact size, making it an ideal system for integration into complex integrated opto-electronic systems networks. However, this advantage comes at a price. Achieving large gain in small volumes introduces significant thermal and electrical transport issues. The enormous gain in bandwidth of the laser and the complicated dependence of gain and refractive index on carrier density, plasma and lattice temperature, makes it particularly challenging for study as a nonlinear dynamical system. A systematic, predictive and robust study requires a multi-faceted first-principles approach that combines the microscopic physics of the light-semiconductor medium interaction with the proper resolution of the spatial and temporal degrees of freedom of the running laser. In this lecture, I will stress features that highlight the need to treat the behavior of the laser at this more sophisticated level beyond the simple and well-used phenomenological single or coupled mode models. The picture that will emerge is that, although in many cases the laser may be running nominally as a single longitudinal mode device, the other suppressed modes are still active and can grow under the influence of weak external perturbation. Wide aperture lasers, designed for high power, high brightness applications, are intrinsically dynamically unstable and display multi-longitudinally-moded chaotic filamentation instabilities. After briefly reviewing various analytic approaches to studying spatio-temporal dynamics in semiconductor lasers, I will discuss specific examples of a low-power external cavity device and a variety of high power wide aperture systems.