Highly collimated laser beams from electrically pumped SH GaAs/GaAlAs distributed−feedback lasers

Utilizing an electrically pumped single−heterostructure GaAs/GaAlAs distributed−feedback laser diode operating in fourth order we have obtained a highly collimated laser beam which is coupled out normal to the plane of the p−n junction rather than through the cleaved end mirrors. This beam is found to have an angular divergence of 0.35° in the dimension determined by the grating and is virtually 100% polarized with the E vector parallel to the grooves of the corrugated feedback structure.