Analysis of astigmatism in high-power semiconductor lasers

A beam profile near the facet of high-power semiconductor lasers is precisely analyzed using two-dimensional computer simulation. Astigmatism and its optical-power dependence can be accurately predicted in this way. Lasers with effective three-layer stab waveguides (i.e. single-step-index waveguides) in the lateral direction have two beam waists. That is, they have a rather large astigmatic distance that depends on the power. To realize high-power lasers with a small astigmatic distance that is relatively independent of output power, waveguides with a graded-index profile or multi-step-index profile are needed.