Parabolic-confocal unstable-resonator semiconductor lasers-Modelingand experiments

摘要

Surface-emitting all-grating-based unstable-resonator lasers,nsuitable for integration with diffractive beam-forming elements, havenbeen experimentally and theoretically studied. The lasers exhibit singlenspatial mode operation for a device width of 160 Μm. The devicenperformance is modeled using a beam propagation method, which accountsnfor spatial hole burning as well as thermal and carrier diffusionneffects. Near- and far-field calculations are incorporated to facilitatenthe comparison with the experimental results. To achieve high-qualitynbeam forming, it is essential that the wavefront of the guided opticalnmode is well defined and stable. Using the model, we study thendependence of the wavefront distortion on various parameters and shownhow these distortions affect the far-field characteristics. The resultsnfrom the simulations agree well with the experimental work. We find thatnthe laser performance is to a large extent controlled by thermalneffects. At low-power operation, these effects can be compensated for,nfor a range of the injection current, by modifications of the resonatornor outcoupler grating geometries