Author：Yong Zhang, Yu He, Xinhong Jiang, Boyu Liu, Ciyuan Qiu, Yikai Su and Richard A. Soref
Abstract：We propose and experimentally demonstrate an ultra-compact and highly efficient
polarization splitter and rotator based on asilicon bent directional coupler structure. The TM-to-TE cross-polarization coupling occurs between the two parallel bentwaveguides, if the phase matching condition is satisfied. Efficientpolarization splitting and rotating are simultaneously achieved. The device is fabricated by a single step of exposure andetching. Themeasured peak TM-to-TEpolarization conversion efficiency reaches 96.9%. The TM-to-TE conversion loss is lower than 1 dB in the wavelength range of 1544 nm–1585 nm, and the insertion loss for the TEpolarization is lower than 0.3 dB in the wavelength regime of 1530 nm–1600 nm. The cross talk values are lower than −20 and −18 dB for the TE- and TM-polarizations over a wavelength range of 70 nm, respectively. The coupling length of thepolarization splitter and rotator is. To the best of our knowledge, our device achieves the shortest coupling length. This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant No. 61235007/61505104, in part by the 863 High-Tech Program under Grant No. 2015AA017001, and in part by the Science and Technology Commission of Shanghai Municipality under Grant No. 15ZR1422800/16XD1401400. We thank the Center for Advanced Electronic Materials and Devices (AEMD) of Shanghai Jiao Tong University for the support in device fabrications.Publishing source：APL Photonics
