Investigation of high-efficiency surface-emitting lasers with blazed grating outcouplers

Grating outcouplers for use in grating coupled surface emitting semiconductor lasers were investigated. For this purpose, horizontal cavity InGaAs-AlGaAs laser oscillators, each integrated with one detuned grating outcoupler, were fabricated using electron beam lithography and chemically assisted ion beam etching. Outcouplers with gratings of both rectangular and blazed profile as well as of different toothwidth-to-period ratios were fabricated and evaluated. Superior differential quantum and surface emission efficiencies of 56% and 84%, respectively, were measured for lasers with optimized blazed outcouplers. This shows that efficiencies comparable to those of conventional edge emitting lasers can be achieved. The measured surface emission efficiencies were also compared with predictions from a theoretical grating analysis.