AN INTEGRATED OPTICAL XY COUPLER FOR PHASE-SENSITIVE OPTICAL POWER COMBINING AND SUPPRESSION OF RADIATED LIGHT

We have designed and fabricated a new type of XY coupler for phase-sen sitive combining of coherent light in waveguide PIC's. The XY coupler uses two input waveguides and couples in-phase light into the middle o f its three output waveguides. Out-of-phase light is coupled into the two outer waveguides. 15.5-dB extinction ratio is demonstrated in a Ma ch-Zehnder interferometer using this new XY coupler. Switching from th e inner to the outer waveguides at the output is also demonstrated.