Dual-pump Phase Sensitive Amplifier Research Articles

Optimization of the conversion efficiency and evaluation of the noise figure of an optical frequency converter based on a dual-pump fiber phase sensitive amplifier.

We propose a new architecture of phase sensitive optical frequency converter based on dual-pump phase sensitive amplification in a highly nonlinear fiber. This frequency converter allows generation of extra tones through nonlinear four-wave mixing between two strong pumps and an input tone. The frequency channel to which the input tone is converted can be chosen by adjusting the phase of the input signal. The conversion efficiency and extinction ratio of this frequency converter are predicted and optimized and its noise figure is calculated using a numerical approach based on the nonlinear Schrödinger equation. A semi-classical noise figure calculation for this approach was used and validated using an analytical fully quantum calculation based on the multi-wave model.

Investigation of the noise figure in a degenerate dual-pump phase-sensitive amplifier using a multi-wave model

A semi-classical seven-wave model is developed to investigate the noise performances of a degenerate dual-pump phase-sensitive amplifier. This approach takes into account the transfer to the signal, through multiple four-wave mixing processes, of the vacuum fluctuations injected into high-order waves. This effect leads to a degradation of the noise figure of the amplifier with respect to the 0 dB value predicted by the usual three-wave model. However, it is proved that a careful choice of the fiber dispersion allows us to use high-order waves to enhance the signal gain without degrading the noise figure above 1 dB.

Influence of multiple four-wave-mixing processes on quantum noise of dual-pump phase-sensitive amplification in a fiber

Phase-sensitive amplification (PSA) based on nonlinear parametric interaction provides low-noise amplification such that the noise figure can be 0 dB in principle. However, when an optical fiber is used as a nonlinear medium for PSA, multiple four-wave-mixing (FWM) processes other than the PSA process are induced, which can degrade the PSA noise performance, especially in dual-pump PSA with a narrow signal-pump wavelength separation. This paper investigates the influence of multiple FWM processes on quantum noise of dual-pump PSA in an optical fiber. The noise figure is calculated using quantum-mechanical operators, considering multiple FWM processes with the PSA process. Calculation examples are also presented, which indicate that the noise figure is degraded by 0.2–0.4 dB from the ideal 0 dB, depending on the signal-pump wavelength separation and fiber parameters.

Investigation of high gain dual-pump phase sensitive amplifiers

In this paper, we investigated a high gain dual-pump degenerate phase sensitive amplifiers. We achieved a 22-dB signal gain with a nonlinear phase shift of 2rad in the 3-nm pump-wavelength separation scheme. Here, we optimized the fiber dispersion to weaken the de-amplification effect of high-order sidebands based on a 27-wave numerical model. By using such a narrow-wavelength-separation dual-pump phase sensitive amplifier scheme, we achieved a 3.3-dB optical signal-noise-ratio improvement compared with that of erbium doped fiber amplifier with the same gain.

Investigation of degenerate dual-pump phase sensitive amplifier using multi-wave model.

Operation of a degenerate dual-pump phase sensitive amplifier (PSA) is thoroughly numerically investigated using a multi-wave model, taking into account high-order waves associated with undesired four-wave mixing (FWM) processes. More accurate phase-sensitive signal gain characteristics are obtained compared to the conventional 3-wave model, leading to precise optimization of the pump configuration in a degenerate dual-pump PSA. The signal gain for different pump configurations, as well as the phase sensitivity, is obtained and interpreted by investigating the dominant FWM processes in terms of the corresponding phase matching. Moreover, the relation between dispersion slope and the width of the signal gain curve versus the pump-pump wavelength separation is revealed, permitting the application-oriented arbitrary tailoring of the signal gains by manipulating the dispersion profile and pump wavelength allocation.

Quadrature Squeezing and IQ De-Multiplexing of QPSK Signals by Sideband-Assisted Dual-Pump Phase Sensitive Amplifiers

Quadrature Squeezing and IQ De-Multiplexing of QPSK Signals by Sideband-Assisted Dual-Pump Phase Sensitive Amplifiers

Efficient phase regeneration of DPSK signal by sideband‐assisted dual‐pump phase‐sensitive amplifier

A high phase sensitivity of 25 dB at the nonlinear phase shift of 0.8 rad in a sideband-assisted dual-pump phase-sensitive amplifier is achieved. Here the sidebands play an important role to evoke larger phase-sensitive attenuations for achieving higher phase sensitivity at such a lower nonlinear phase shift. This feature is utilised to improve the efficiency in the phase regeneration of 21.5 Gbit/s DPSK signals. The phase error of 22.6° was squeezed to 2.5° by operating such a sideband-assisted dual-pump phase-sensitive amplifier at 0.8 rad nonlinear phase shift. The operations at low nonlinear phase shift enable utilisation of the state-of-the-art silica-based highly nonlinear fibre with low noise and low dispersion slope by avoiding stimulated Brillouin scattering induced by higher pump power.

Evolution of the gain extinction ratio in dual-pump phase sensitive amplification

We have experimentally achieved a gain extinction ratio (GER) of 30 dB at 21.75 dBm pump power in a dual-pump phase sensitive amplifier based on highly nonlinear fiber, which is more efficient than what we predict with the conventional three-wave model. We point out that high-order sidebands play a key role. Then we scrutinize the trajectories of the output signal vector in the complex plane with increasing nonlinear phase shift and understand the roll-over behavior of GER versus pump power curve. We found that the phase "flip" of the output signal occurs around the largest GER. Adjusting design parameters, we show how to improve GER.

RZ-DPSK signal regeneration based on dual-pump phase-sensitive amplification in fibers

All-optical regeneration of differential phase-shift keying signals by means of a phase-sensitive amplification scheme solely based on highly efficient four-wave mixing in fibers is theoretically and numerically studied. The analytical and numerical investigation demonstrates almost ideal phase regeneration accompanied with enhanced amplitude noise suppression in the regime of pump depletion