Design of wide-emitter single-mode laser diodes

An accurate laser simulator is developed to investigate the influences of various device parameters on modal discrimination and beam quality to optimize the brightness of semiconductor lasers. Previous work using the Prony method is extended, both by using a more robust laser simulator to solve for the optical fields and by extending the Prony method to operating conditions above threshold. The semiconductor laser model is used to investigate the effects of various device parameters on the characteristics of a gain-guided 980-nm Al-free stripe geometry laser. The device parameters investigated are the device geometry, the thickness and doping level of the waveguiding layer and the front facet reflectivity. Together with practical and economic considerations, the device parameters of a wide emitter gain-guided laser are optimized. The optimized gain-guided laser is predicted to operate in the fundamental mode up to 1.15 W. At this maximum fundamental mode power, the slow axis beam divergence at 1/e² points is 5.4°, the beam quality factor M² is 1.62, the astigmatism is 27 μm, and the brightness is 61 MW/cm²sr.