Tunable Polarization Rotator Based on SOI Platform for Optical Communications Systems

Abstract

A compact polarization rotator (PR) based on silicon on insulator (SOI) platform with nematic liquid crystal (NLC) is introduced. The NLCs are anisotropic materials which can be used to improve the modal hybridness of the hybrid modes. As a result, a polarization rotation can be achieved over a short propagation distance. The proposed PR is analyzed using the full-vectorial finite-difference method and the full-vectorial finite-difference beam propagation method. The numerical results reveal that at the operating wavelength of 1.55 μm, the PR has a compact device length of 11.67 μm with 15.5 dB extinction ratio (ER) for both polarization conversions. The insertion losses of the reported PR are equal to 0.29 dB and 0.59 dB for TE to TM and for TM to TE conversions, respectively. Moreover, it offers a broad bandwidth of (860 -1780 nm) for TE to TM and (890 -1790 nm) for TM to TE with an ER better than 10 dB. The fabrication tolerances and influences on the performance of the PR for the different structure geometrical parameters and operating wavelength are also investigated.