Coherent surface-emitting diode laser array with narrow far-field output

A coherent seven-element linear array of injection-coupled grating surface-emitting (GSE) diode lasers1 has been demonstrated. The array, shown in Fig. 1(a), consisted of seven pumped gain sections and eleven distributed Bragg reflector (DBR) sections with second-order gratings on a common planar waveguide. These DBR sections provide the optical feedback necessary to sustain laser operation, act as output couplers, and establish optical coupling between the electrically independent gain sections. This array had an external differential quantum efficiency of 15%, a single-line spectral output with sidemode rejection from 15 to 27 dB, and operated at peak powers of over 400 mW—the highest yet reported for a GSE laser array.