We have demonstrated the first 2-D arrays of surface emitting distributed feedback lasers (SEDFBs). The SEDFB structure is illustrated in Fig. 1. It uses a metal grating as its p-contact. The grating period is tuned to make the lasing resonance coincide with the gain peak of the laser material. The p-layer is very thin so that the evanescent tail of the waveguide mode couples into the grating layer, giving rise to diffracted radiation both into the surface normal for the output beam and backward along the guide for feedback. The grating surface is coated with gold to produce a large diffraction efficiency and low loss. A chemical etch of the substrate down to the n-cladding AlGaAs layer surface permits emission of the diffracted output beam through an opening in the n-contact metal. The regions between the elements were not electrically pumped to prevent cross-coupling. Single element SEDFBs have already produced as much as 400 mW pulsed and 65 mW cw at the time of this writing.
© 1989 Optical Society of AmericaPDF Article