High efficiency surface-emitting laser with subwavelength antireflection structure

Abstract
We report on a high efficiency tapered grating surface-emitting laser with an antireflection-structured (ARS) substrate. A 64% improvement of the device efficiency is obtained by monolithic integration of a sawtooth-shaped ARS on the GaAs substrate. Slope efficiencies of 0.82 W/A were measured at 975 nm in pulse pumping and are mainly limited by free-carrier absorption in the n-doped GaAs substrate. A maximum peak power of 25 W was obtained without coating the device's cleaved facet. The symmetry of the near-field intensity profile along the grating coupler is improved by varying the grating duty cycle from 20% to 55%.