Lateral refractive index step in GaAs/AlGaAs multiple quantum well waveguides fabricated by impurity-induced disordering

The lateral refractive index step Δn in GaAs/AlGaAs multiple quantum well waveguides fabricated by impurity-induced disordering is determined. Δn is found to depend on polarization and wavelength, increasing towards the active-layer band gap. The lateral index step can be as large as 4×10−2 for a Zn disordered waveguide device at 875 nm. A strong birefringence of the waveguiding characteristics is observed leading to an antiguiding behavior of TM-polarized light for wavelengths sufficiently below the band gap.