Phase-Sensitive Amplified Transmission Links for Improved Sensitivity and Nonlinearity Tolerance

Abstract

In this paper, we investigate the properties of transmission links amplified by phase-sensitive amplifiers (PSAs). Using an analytic description, we explain the principles enabling improved sensitivity compared to conventional links amplified by phase-insensitive amplifiers (PIAs) and mitigation of nonlinear transmission distortions. We demonstrate these features using numerical simulations, and in particular, we show the possibility of efficiently mitigating both self-phase modulation (SPM)-induced distortions and nonlinear phase noise (NLPN) if the link dispersion map is optimized. The properties of the noise on signal and idler are important and to enable NLPN mitigation, the noise must be correlated at the link input. We investigate the role of the dispersion map in detail and show that in a link with standard single mode fiber (SSMF) the optimum dispersion map for efficient nonlinearity mitigation corresponds to precompensation of an amount equal to the effective loss length. Furthermore, we experimentally demonstrate both improved sensitivity and mitigation of nonlinearities in a 105 km PSA-amplified link transmitting 10 GBd 16-ary quadrature amplitude modulation (16QAM) data. We measure a combined effect allowing for more than 12 dB larger span loss in a PSA-amplified link compared to a conventional PIA-amplified link to reach the same bit error ratio (BER) of 1 × 10 −3 .

Improved mitigation of self-phase modulation induced impairments in 28 GBaud phase-sensitive amplified links

“…In [2] and [22] it is noted that different GVD parameter value for a 8 nm wavelength separation does not have significant impact on the SPM induced nonlinearity mitigation performance of a PSA link. At the end of each transmission span, the loss of the transmission span was compensated by PSA or PIA amplification.…”

“…The phase-sensitive amplification process was modeled using a simplified model, shown in Fig. 1, under the assumptions that the PSA was operating in a high-gain regime with low signal input powers [2,6]. The signal S n and idler I n are both amplified by the gain necessary to compensate the span loss and then separated for conjugation and constellation alignment processes.…”

“…regarding the dispersion map optimization for in-line dispersion compensated PIA links has been carried out [18][19][20], but these principles are not directly applicable to PSA links, since the effectiveness of the nonlinearity mitigation in PSA links is highly dependent on correlation properties of propagated signal and idler waves. It has been shown previously that the dispersion management for a single-span dispersion map optimized PSA link [2,11,21] and for a two-span dispersion map optimized PSA link [22] plays an important role for the nonlinearity mitigation performance. The importance of dispersion map optimization for twin-waves was first noted in [13], where according to the first-order perturbation theory, a symmetric span power map with an anti-symmetric dispersion map should be used for the best nonlinearity mitigation performance for the PCTW approach.…”

Fiber nonlinearity mitigation of WDM-PDM QPSK/16-QAM signals using fiber-optic parametric amplifiers based multiple optical phase conjugations

“…Several approaches have been proposed to mitigate the fiber nonlinearity, in both the digital and the optical domain, such as digital back propagation [3,4], frequency-referenced transmission [5], phase-conjugated twin waves [6], phase-sensitive amplification [7] and optical phase conjugation [8][9][10][11][12][13][14][15]. Among these schemes, optical phase conjugation (OPC) offers unique benefits, including modulation-format transparency, capability of processing high speed and heterogeneous signals, capability of operating on an entire wavelengthdivision-multiplexed (WDM) band at the same time, and little additional latency.…”

Mitigation of Nonlinear Effects on WDM QAM Signals Enabled by Optical Phase Conjugation With Efficient Bandwidth Utilization

“…Several approaches have been investigated, in both the digital and optical domains, in order to compensate for deterministic nonlinear impairments. They include: digital back-propagation [4], phase sensitive amplification [5][6][7], phase-conjugated twin waves [8], multiple OPCs [9,24], and mid-link OPC [11][12][13][14][15][16][17][18]. Amongst these, mid-link OPC, located at exactly the middle point of the transmission link has regained some momentum in recent years due to the exceptional performance it allows for a relatively simple modification of the overall system.…”