Curved-grating, surface-emitting distributed feedback lasers

Surface-emitting distributed feedback (SE-DFB) lasers have a gold-coated grating on the p-contact surface that provides feedback and diffracts guided-mode radiation into the surface normal. To date, broad-area SE-DFB devices have produced as much as nine watts cw output power and 27 percent total "wall-plug" efficiency under continuous wave operating conditions. Grating chirp has been shown to improve the output efficiency as well as produce nearly diffraction-limited beam quality along the longitudinal direction. However, the lateral beam quality of broad area SE-DFB laser has been poor due to multi-mode operation and filamentation.