Coherent lithium niobate receiver chip for reset-free polarization control

In coherent optical receivers continuous state of polarization (SOP) matching of the local oscillator and received signal must be achieved, e.g. by polarization scrambling, polarization diversity or polarization transformation. The authors report on a packaged integrated-optical LiNbO3 chip comprising optical compensators for endless polarization control and a tunable 3 dB coupler.