Birefringent channel waveguides defined by impurity-induced superlattice disordering

The waveguiding characteristics of GaAs/AlGaAs channel waveguides defined by silicon-induced superlattice disordering were investigated at 1.15 μm wavelength. These waveguides guide laterally only TE-polarized light. Because of the birefringence of the superlattice core of the waveguide, only the TE mode experiences a positive refractive index step between the unmixed and disordered superlattices. The TM mode, on the other hand, experiences a negative refractive index step resulting in antiguiding. The operation of these waveguides as efficient waveguide polarizers is demonstrated.