´Nonwaveguide´-mode semiconductor injection lasers

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