Curved-grating, surface-emitting DFB lasers and arrays

A new method of producing nearly diffraction limited beam quality from high-power semiconductor lasers is presented. It is shown, both theoretically and experimentally, that well-designed grating curvature in surface-emitting distributed feedback lasers can alleviate the problems of multi-mode operation and filamentation in wide stripe devices. Surface-emitting devices of this type are capable of very high power without the optical damage limitations of edge-emitting lasers. A method for combining arrays of these lasers with series electrical wiring and precision optical alignment has been developed. A 64 element array was demonstrated that produced similar to 160 W of cw power and could be focused into a small spot.