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Fabrication Of Grating-surface-emitting Semiconductor Lasers

A sketch of a grating-surface-emitting (GSE) laser is shown in Fig. 1. The gratings between the gain sections provide feedback for laser oscillation in second order and couple out the laser radiation perpendicular to the surface in both directions in first order. With proper choice of grating parameters, a portion of the light is passed completely through each grating section and serves to injection lock additional gain sections in the longitudinal direction. GSE laser array technology has experienced steady progress over the last two years [ 11. Improvements in material quality and uniformity have made it possible to coherently couple two dimensional GSE lasers over distances larger than 1 cm. These devices can produce peak outputs of 32 W per surface and continuous power outputs of over 3 W per surface With differential quantum efficiencies of > 40 % per surface. Variations on the basic GSE laser concept have resulted in Master Oscillator Power Amplifier (MOPA) GSE arrays [2,3] and GSE devices with active grating outcoupling [4,5]. GSE arrays with 10 elements per gain section and 20 gain sections have obtained cw threshold current densities of under 140 A/cm2. Linewidths in the 30 to 60 MHz range have been obtained with output powers of 100 to 250 mW/surface.