114Tb/s DP-QPSK WDM polarization-diverse optical phase conjugation

Abstract

Optical phase conjugation (OPC) of a polarization-multiplexed comb of 10x114Gb/s DP-QPSK signals has been demonstrated for the first time, occupying a spectral bandwidth of >1THz (~9nm). The nonlinear element employed for the OPC was highly nonlinear fiber (HNLF) optimized for the suppression of stimulated Brillouin scattering (SBS) and configured in a bi-directional loop offering polarization diversity. Pump power (each way about the loop) and input signal power to the OPC subsystem were optimized at 29.7dBm and + 3dBm respectively producing a Q 2 penalty of ≤0.9dB over all conjugate wavelengths, polarizations and output OSNR (up to 20dB).

20 dB net-gain polarization-insensitive fiber optical parametric amplifier with >2 THz bandwidth

“…a Mach-Zehnder interferometer using a length of HNLF in each arm (but requiring active path alignment) or a 'diversity-loop' Sagnac interferometer arrangement with a single length of HNLF. The diversity loop has been successfully demonstrated using PDM signals for OPC applications [9,10], but is inherently limited for FOPA net-gain amplification due to pump distortions arising from Stimulated Brillouin Scattering (SBS) and Four-Wave Mixing (FWM) of bi-directional pump components [11].…”

Enhanced superchannel transmission using phase conjugation

“…The signals propagated through this link a number of times (which included a gain flattening filter and an amplifier to overcome loop specific losses), before entering the dual OPC. Here the two groups of 5 x 400Gbit/s superchannels were amplified, split into two parallel paths using a wavelength selective switch (WSS), giving ~12dBm total power per band, and conjugated in two nearly identical single pump polarisation-diverse OPCs 10 . The OPCs used independent pump lasers and aluminium doped highly-nonlinear fibres with lengths, fibre loss and nonlinear coefficients of 100m, 6.3dB/km and 6.9/(W.km) respectively.…”

Kerr nonlinearity mitigation in 5 × 28-GBd PDM 16-QAM signal transmission over a dispersion-uncompensated link with backward-pumped distributed Raman amplification

“…In order to mitigate the signal transmission impairments due to Kerr nonlinearity, various techniques involving electronic domain compensation [6][7][8][9] as well as optical domain compensation [10][11][12][13][14][15][16][17][18][19][20] have been investigated. It has been shown in [10,13] that systems with bi-directional distributed Raman amplification (DRA) have power-dispersion maps which make them much more suitable for fiber nonlinearity mitigation through optical phase conjugation (OPC) than pure EDFA amplified links.…”

“…Consequently, the nonlinear distortions that have been accumulated in the first half of the link are compensated for in the second half of the link [10][11][12]. Recent studies on design and performance evaluation of OPC devices based on non-degenerate FWM have been performed in a 100-GHz spaced 10 × 114-Gb/s PDM QPSK system [15]. In addition, WDM systems with up to 8-channels using PDM 16-QAM signals have been used to characterize an OPC device that employs a non-degenerate FWM process [16,17].…”