Optical Couplers for Coherent Optical Phase Diversity Systems

摘要

Optical couplers, used in coherent optical phase diversity systems, are analyzed. On the basis of the coupled modes propagation theory, expressions for the output optical fields are obtained. The signal to noise ratio (SNR) at the output of a receiver using these couplers is computed. The variation of SNR with changes of the coupling coefficient is examined for various couplers. The influence of coupling losses is also investigated. The analysis favors two schemes: a three fiber coupler and a four fiber coupler. When the relative noise intensity (RIN) is substantial the four fiber device is best. Three fiber couplers are best when RIN is negligible.