Beam divergence of the emission from double-heterostructure injection lasers

Abstract

Far‐field emission patterns of GaAs–Al_xGa_1‐xAs double‐heterostructure lasers have been measured to determine the dependence of the beam divergence as a function of active layer thickness d and composition x. The beam divergence in the plane of the junction θ_∥ is ∼ 10°, while the beam divergence perpendicular to the junction plane ${\theta }_{\perp }$ is considerably larger and depends strongly on d and x. Curves are given for ${\theta }_{\perp }$ and the confinement factor Γ as a function of d between 0.05 and 2.0 μ for x = 0.1, 0.2, 0.3, and 0.4. These curves were calculated by considering the laser as a dielectric waveguide with a refractive index step between GaAs and Al_xGa_1−xAs.