  Uniaxially patterned dielectric layers have an optical anisotropy that can be
externally controlled. We study the effects of patterning the cladding or the
core layer of a 3-layer optical waveguide on the polarization properties of
propagating radiation. Particular attention is paid to the case when the core
material is a semiconductor with optical gain. We discuss a number of devices
based on incorporating an uniaxially patterned layer in the structure design,
such as a polarization-insensitive amplifier, a polarizer, an
optically-controlled polarization switch, and an optically controlled modal
coupler.
