Design and fabrication of photonic crystal based polarization rotator for THz applications

Polarization rotator is a crucial element in an integrated optic circuit. All passive polarization rotator structures are composed of geometrically asymmetric structures. The existing polarization rotator structures are bulky that makes it impossible to analyze them using rigorous numerical methods. The fabrication process of high index contrast slanted wall waveguide that are more compact (~15 mum) in comparison with other types are not compatible with planar integrated circuit. We have introduced a novel and compact photonic crystal based (PC) polarization rotator that consists of periodic asymmetric loaded PC slab waveguide. The structure is designed using coupled-mode theory and 3D-FDTD. The total length of the device is 12lambda. A membrane PC slab technology is developed for THz application and the proposed devices are implemented utilizing this technique.