Ultrasmall PBS-integrated coherent mixer using 1.8%-delta silica-based planar lightwave circuit

A silica-based planar lightwave circuit (PLC) is developed as an optical front-end for polarization-diversity digital-coherent receiver, where polarization-beam splitters and 90-degree optical-hybrid mixers are integrated in a small-size (12mm×12mm) PLC chip employing a relatively large refractive-index difference of 1.8%.