Ultrasmall Si-nanowire-based polarization rotator

A polarization rotator based on asymmetrical Si nanowires is presented and optimized for high polarization rotation efficiency (almost 100%). The present polarization rotator has a very small conversion length (similar to 10 mu m) and consequently becomes very compact. The analysis of the wavelength dependence shows the present polarization rotator has a broad bandwidth (similar to 120 nm) for high conversion efficiency (> 97%). The tolerance to various fabrication errors is also numerically studied. To compensate the fabrication error, a post-compensation method is introduced by modifying the refractive index of the up-cladding. (c) 2008 Optical Society of America.