Balanced phase and polarization diversity coherent optical receiver

A balanced phase and polarization diversity receiver employing a compact bulk optical 90 degrees hybrid and a silicon bipolar multiplier IC is described. The compact bulk optical hybrid provides all required optical signals with well-defined phase relations in a single unit and is therefore a good solution of the problems associated with the complex structure of the optical part of the receiver. The multiplier IC has a dynamic range of at least 15 dB. It guarantees that variations of the signal power in the different detection branches of the receiver cause negligible degradation in both diversity operations. The receiver has been tested in a 565-Mb/s DPSK transmission system.<>