Electro-optic controllable transverse electric/ transverse magnetic polarization converter based on the GaN/Al0.3Ga0.7N superlattice waveguide

An electro-optic controllable transverse electric/transverse magnetic (TE/TM) polarization converter based on the GaN/Al0.3Ga0.7N superlattice waveguide is proposed for actively controlling the output polarization state. We use the highly accurate and efficient hill-vector mode-matching method to evaluate its performance. The result indicates that the output polarization state can be actively controlled in a full 0 degrees-90 degrees range by applying the adjustable voltage on this converter, and that a full TE <--> TM conversion is also realizable by applying no voltage. Moreover, this converter has a high conversion efficiency of 99.9%, a low insertion loss of 0.03 dB, and a wide bandwidth (FWHM) of 200 nm. We further investigate the deviation effect of the etching width or the operating wavelength on TE <--> TM conversion. In order to counteract deterioration on conversion efficiency brought on by the deviation, a simple compensation method is presented by actively adjusting the voltage to a certain value. (C) 2018 Optical Society of America