Full quadrature regeneration of QPSK signals using sequential phase sensitive amplification and parametric saturation

Abstract

We demonstrate all-optical regeneration of both the phase and the amplitude of a 10 GBaud quadrature phase shift keying (QPSK) signal using two nonlinear stages. First we regenerate the phase using a wavelength converting phase sensitive amplifier and then we regenerate the amplitude using a saturated single-pump parametric amplifier, returning the signal to its original wavelength at the same time. We exploit the conjugating nature of the two processing stages to eliminate the intrinsic SPM distortion of the system, further improving performance.

In-Band OSNR Measurement Method for All-Optical Regenerators in Optical Domain

“…The simulation results are shown in Figure 3, and the OSNR values are normalized to the 0.1 nm bandwidth. It can be seen from Figure 3 that, when the input power ratio between Pump1 and the QPSK signal ρ = 2 dB, the output OSNR reaches the maximum of about 26 dB, in agreement with the experimental value presented in [6], which indicates the validity of our simulation setup.…”

“…The proposed method is verified by simulating the OSNR of regenerated QPSK signals, in comparison to the EVM calculation. For the QPSK regenerator composed of the PSA and amplitude shaping units as given in [6], the OSNR can be improved by more than 3 dB in the input OSNR range of 10 to 26 dB of interest in the communication system. Moreover, this method can be applied to the various QPSK regenerators at different data rates.…”

“…As an example, to verify the feasibility of the proposed measurement method, we performed simulations and took the optical QPSK regenerator (similar to [6]) into account. The corresponding block diagram is shown in Figure 2.…”

“…Different from fiber dispersion and nonlinearity, it cannot be eliminated by some compensation methods. In this case, all-optical regeneration technology has attracted much attention [3], especially to high-order modulation signal regeneration, such as multi-level amplitude regeneration based on nonlinear interference structure [4,5], multi-stage phase regeneration based on phase-sensitive four-wave mixing (FWM) [6,7], and several regeneration schemes of quadrature amplitude modulation (QAM) signals [8,9].Just like in-line EDFAs, all-optical regenerators are usually integrated into the intermediate nodes of optical links. However, most of the previous studies paid more attention to the regeneration performance in the electrical domain, instead of the optical domain.…”

QPSK Signal Regeneration Based on Vector Phase Sensitive Amplification With Low Pump Powers

“…There is a myriad of all-optical QPSK signal regeneration researches based on the coherent addition of signal and its conjugate harmonic(s) using phase-sensitive (PS) processes [5]- [7]. This PS process, historically known as ''phase sensitive amplification (PSA)'', is one of the most widely used method so far to regenerate phase coded signals.…”