Abstract

In the last several years, considerable work has been directed toward developing surface-emitting semiconductor lasers such as the vertical cavity, etched 45° facet, and grating-coupled surface emitter (GSE). In this paper we review the grating-coupled approach to surface-emitting semiconductor lasers, which has demonstrated monolithic integration of over one hundred semiconductor lasers into a coherent array with the capability of electronic beam steering. Coherent operation is obtained by mutual injection coupling in one direction and evanescent coupling in the other. The threshold current density and efficiency of these lasers are approaching that of conventional cleaved facet lasers. Transparent substrates allow junction down mounting for improved thermal packaging. GSE arrays have been fabricated with wavelengths ranging from 0.77 to 0.88 µm using the AlGaAs material system, from 0.88 to 1.05 µm using strained-layer GaInAs quantum wells, and at 1.3-1.5 µm using the GaInAsP material system. To obtain the ultimate performance from the GSE arrays will put significant demands on the layer uniformity of the semiconductor structure and the fabrication processes. Uses for GSE lasers include incoherent 2-D arrays for pumping solid state lasers, high speed interconnects for integrated circuit chips, and space communications.

© 1989 Optical Society of America