Lateral mode selection in semiconductor injection lasers

Various methods have been used to control the lateral modes of injection lasers. We report on lateral mode selection in continuous-wave double-heterojunction lasers using the differential diffraction losses of different modes at a narrow reflector stripe on one emitting facet. Power output curves and far-field beam patterns scanned in the lateral (junction) plane are shown both before and after an antireflection coating was deposited on one facet except in a narrow stripe. The stripe defines the mode-selecting reflective region. Calculations, based on a simple model of DH injection lasers, are made by estimating the magnitude of the effect. Output powers of 12 mW from one facet were obtained.