'Nonwaveguide'-mode semiconductor injection lasers

Double-heterostructure AlGaAs (0.83 micron) and GaInPAs/InP (1.26 microns) injection lasers, operating in a 'nonwaveguide' mode have been prepared and studied. The axis of a Fabry-Perot cavity was inclined to the active layer plane, and so laser emission had to penetrate through the transparent wide-bandgap cladding layers of the heterostructure. Tilting angles were chosen from 10 to 15 deg to prevent waveguide propagation of laser emission along the active layer. Laser action with pulse excitation, including room-temperature operation at a wavelength of 1.26 microns, was observed, and the divergence of the laser beam was found to be several times less in the nonwaveguide configuration (5-8 deg) than in the usual device (40-50 deg). Threshold current considerations and comments on device preparation are also given.