Theoretical study of beam quality improvement in broad area semiconductor devices

M. Radziunas, K. Staliunas

Weierstrass Institute, Berlin , Germany

Broad area (BA) lasers are robust, compact, high power and highly efficient devices, which, however, suffer from a poor spatial and temporal beam quality. The stabilization of the laser beam in a BA laser can be achieved, for example, by injection of the optical beam at some angle to the longitudinal axis or by the external optical feedback from the corresponding off-axis mirror or grating. An introduction of 1d or 2d-periodic structures on the electrical contact can also help to improve the quality of the generated beam in BA lasers or of the amplified beam in BA amplifiers. In this talk some of these schemes allowing an improvement of the beam quality in the BA devices will be discussed. Our theoretical study is based on the simulations of the 2+1-dimensional traveling wave model which takes into account the spatio-temporal dynamics of slowly varying complex amplitudes of the counter-propagating optical fields, induced polarizations and carrier densities. A proper resolution of the fast oscillating fields, as well as the resolution of a sufficiently large optical frequency range, requires a fine space (up to $10^6$ mesh points) and time (up to $10^6$ points for typical 5ns transient) discretization. The resulting large numerical scheme is solved using multilevel parallel distributed computing, that allows us to run long time dynamic simulations over large parameter ranges in reasonable time. Comparable computations on a single PC system take nearly 100 times longer.