Publications

Fabrication issues for a chirped, subwavelength form-birefringent polarization splitter

Kemme, S.A.; Wendt, J.R.; Vawter, Gregory A.; Cruz-Cabrera, A.A.; Peters, D.W.; Boye, Robert B.; Alford, C.R.; Carter, T.R.; Samora, S.

We report here on an effort to design and fabricate a polarization splitter that utilizes form-birefringence to disperse an input beam as a function of polarization content as well as wavelength spectrum. Our approach is unique in the polarization beam splitting geometry and the potential for tailoring the polarized beams' phase fronts to correct aberrations or add focusing power. A first cut design could be realized with a chirped duty cycle grating at a single etch depth. However, this approach presents a considerable fabrication obstacle since etch depths are a strong function of feature size, or grating period. We fabricated a period of 1.0 micron form-birefringent component, with a nominal depth of 1.7 microns, in GaAs using a CAIBE system with a 2-inch ion beam source diameter. The gas flows, ion energy, and sample temperature were all optimized to yield the desired etch profile.