Phase-and-amplitude regeneration of differential phase-shift keyed signals using a phase-sensitive amplifier

Abstract

DPSK phase-and-amplitude regeneration with a NOLM-based phase-sensitive amplifier is demonstrated experimentally. For a highly degraded input signal, maximum differential phase errors were reduced from 82 degrees to 41 degrees , while the SNR was improved by more than 5-dB. Differential phase Q-factor improvement was better than 6-dB. The PSA was operated free of excess noise due to stimulated Brillouin scattering by using a binary phase modulated pulse train as the pump. The impact of pump fluctuations on regeneration performance is clarified. The regenerated signal was characterized by measurement of the constellation diagram by linear optical sampling, giving the first directly measured evidence of DPSK phase regeneration.

Effect of input phase modulation to a phase-sensitive optical amplifier

“…Phase modulation is often used in optical communication, such as in phase-shift keying. Signals from phase-shift keying are often demodulated using homodyne or heterodyne techniques and phase sensitive amplifiers have been investigated for regeneration of phase keyed signals [12]. A theoretical and experimental examination of a single-ended coherent receiver based on a phase sensitive fiber parametric amplifier, including a comparison to a single-ended homodyne detector, has been presented in [13].…”

Distributed Measurement of Signal Power Evolution in a Phase Sensitive Parametric Amplifier

“…As a noticeable consequence, PS-FOPAs allow noise-free amplification of the in-phase signal and permit a drastic reduction of the noise figure in optical communications links, hence an increase in capacity [1]. Furthermore, phase sensitive amplification allows many ultrahigh speed processing functions of multi-level phase and amplitude coded signals including phase regeneration [2].…”

Overcoming Electronic Limits to Optical Phase Measurements with an Optical Phase-only Amplifier

“…Photonic signal processing is increasingly finding applications in several fields previously dominated by electronics, including analogue-to-digital conversion (ADC) [1], microwave and terahertz wave generation [2,3], radio-overfiber (ROF) [4], and all-optical regeneration [5]. The benefits of utilizing photonic methods over the electronic equivalent are numerous, including low transmission loss, flat and broadband spectral response, and crucially for ADC applications, lower jitter sampling [1].…”