Signed and Accurate Measurement of Phase Offset in Optical DPSK Demodulator

Abstract-A signed and accurate phase offset estimation method of the delay interferometer (DI) for the direct detection differential phase-shift keying system based on a delay-tap sampling technique has been demonstrated. A chromatic dispersion offset module was introduced to help the phase offset measurement. The proposed method can not only measure the value but also distinguish the polarity of phase offset of DI. The measurement sensitivity can reach ±4° and measurement range can reach ±75°. The simulation and experimental measurement results are in close agreement with each other.