Strained-Layer Superlattices for Polarization-Insensitive Integrated Waveguide Applications

Abstract

Quantum well intermixing has emerged as a new method to define waveguides in semiconductors. Selected regions in a semiconductor quantum well structure are altered using dielectric cap disordering, laser induced disordering or impurity induced disordering (IID) thus creating a refractive index discontinuity at the diffusion boundary. The chief advantage of using multiple quantum wells in disordered structures is that it is possible to control the electronic and optical properties of multiple-quantum wells and superlattices by varying the layer widths and compositions. This creates great potential for designing waveguides, since quantum-size effects and strain effects can be used to obtain a range of superlattice designs which display desirable characteristics such as polarization insensitivity to the propagating light. Also, since IID provides a way to create waveguides in superlattices using conventional IC processing techniques, it is an attractive process to be considered for fabricating optoelectronic integrated circuits.