The analysis of an optical differential phase decoder

An optical heterodyne differential phase decoder combines PM/AM converter and balanced detector in a polarized common-path optical heterodyne interferometer is presented. The performance of the decoder is demonstrated theoretically and experimentally. The minimum detectable phase 8.9 × 10^-7 rad/Hz¹2/ of proposed phase decoder is achieved with 0.5 mW of incident laser power. In principle, the minimum detectable phase can be further improved to 3 × 10^-9 rad/Hz¹2/, which in comparison with 9 × 10^-10 rad/Hz¹2/ developed by other group, in case of ideal optical heterodyne interferometer and 1 watt of incident laser power are employed.