PDM Signal Amplification Using PPLN-Based Polarization-Independent Phase-Sensitive Amplifier

Abstract

We demonstrate the first polarization-independent phase-sensitive amplification of a polarization-division multiplexing (PDM) signal. A novel polarization-diversity loop configuration using periodically poled LiNbO 3 waveguides is proposed to achieve the polarization-independent amplification of both a single-polarized signal and a PDM signal. The proposed configuration provides two independent optical parametric amplification processes for two orthogonal polarization components in the loop, while preventing the amplification of the reflection noise by a counter-propagating pump. Polarization-independent error-free operation was confirmed with a bit-error-rate measurement for a 40-Gb/s quadrature phase-shift keying (QPSK) signal. We then demonstrated the phase regenerative amplification of an 80-Gb/s PDM-QPSK signal with artificial phase noise.

The impact of parametric noise amplification on long haul transmission throughput

“…Positive conversion efficiencies have only been observed for fibre devices acting as parametric amplifiers and employing SBS suppression techniques [23][24][25], however, parametric gain has recently been reported in a PPLN device [35]. Data points are taken from [24][25][26][27][28][29][30][31][32][33][34][35]. Figure 2b illustrates the achieved performance improvements for systems employing both OPC and coherent detection, alongside the anticipated theoretical performance enhancement.…”

“…High channel counts have been observed for PPLN devices [29] where crosstalk is low, and for dispersion engineered optical fibres [24][25][26][27][28]. Positive conversion efficiencies have only been observed for fibre devices acting as parametric amplifiers and employing SBS suppression techniques [23][24][25], however, parametric gain has recently been reported in a PPLN device [35]. Data points are taken from [24][25][26][27][28][29][30][31][32][33][34][35].…”

“…With only one exception, a short (24km) Raman amplified link [28], maximum performance gains are limited to around 2.7 dB, well below the theoretical limit. This is due to a combination of PMD, dispersion slope and power asymmetry reducing the efficiency of the nonlinearity compensation, the OSNR degradation due to conversion loss, and the crosstalk induced by unwanted nonlinear processes in the OPC device [35]. Techniques to improve power symmetry have already been proposed [27][28]37] and solutions to the remaining issues will undoubtedly follow.…”

Parametric Amplifiers in Optical Communication Systems: From Fundamentals to Applications

“…On the other hand, it does not require the bandwidth of the copropagating idler wave. This work was also extended to cover polarization division multiplexed transmission [41].…”

Experimental demonstration of Raman-assisted phase sensitive amplifier with negligible gain/power fluctuation

“…To replace an EDFA in field with the PSA, there are two major issues, such as polarization dependence and phase fluctuation. Polarization dependence has been mitigated by a polarization-diverse scheme with a bi-directional loop configuration [2,3]. The second one is phase fluctuation.…”