The relation between the phase shift and the mean optical power (MOP) output from a delay-line interferometer (DLI) port applied for phase-shift keying (PSK) signal demodulation is proven of a cosine law irrelevant to signal modulation condition. The variation amplitude of the MOP is proportional to the transition duration of the modulation pulses. This phenomenon is interpreted as the result of the statistical and waveform characteristics of the PSK. The conclusions verified by simulation and experiment are generalized to other modulation formats and then applied to phase detuning monitoring, delay time judgment of DLI, and independence of modulation data assessment.
© 2012 Chinese Optics Letters
(060.5060) Fiber optics and optical communications : Phase modulation
(070.1170) Fourier optics and signal processing : Analog optical signal processing
(120.3180) Instrumentation, measurement, and metrology : Interferometry
Fiber Optics and Optical Communications
He Wen, Jinxin Liao, Xiaoping Zheng, Hanyi Zhang, and Yili Guo, "Phase shift monitoring of delay-line interferometer and its application in phase-shift keying signal system," Chin. Opt. Lett. 10, 070601-070601 (2012)