Investigation of a novel optical phase demodulator based on sampling phase-locked loop

Abstract—A novel phase-locked coherent demodulator, based on a sampling phase-locked loop, is presented and investigated theo-retically. The demodulator is capable of operating at high frequen-cies, by using optical sampling to downconvert the high-frequency input radio-frequency signal to the frequency range of the base-band loop. We develop a detailed theoretical model of the (sam-pling) phase-locked coherent demodulator and perform detailed numerical simulations. The simulation results show that the oper-ation of the sampling demodulator resembles the operation of the baseband demodulator for very short optical pulses (<2 ps). Fur-thermore, we investigate how the signal-to-noise ratio of the de-modulator is affected by timing and amplitude jitter of the pulsed optical source. Index Terms—Analog links, coherent, microwave photonics, modulators, phase-locked loop (PLL), phase-modulation, sampling. I