Investigation of the refractive index profiles of multilayer Ga1–xAlxAs laser heterostructures

The method of spatial modulation of the reflection of light from a cleaved section was used to find the refractive index profiles of three- and four-layer Ga_1–xAl_xAs laser heterostructures (with GaAs substrates). The dependences of the concentration of Al in Ga_1–xAl_xAs solid solutions and of the band gap on the coordinate perpendicular to the plane of growth were calculated. A spatial resolution of ~0.4 μ was achieved, the sensitivity in the determination of the gradient of the refractive index n was ~10^–4 μ^–1 and the absolute error in the measurement of the layer thicknesses was ~0.05 μ (for layers more than 0.4 μ thick).