Abstract
In this work, we propose and experimentally demonstrate a novel low-complexity technique for fiber nonlinearity compensation. We achieved a transmission distance of 2818 km for a 32-GBaud dual-polarization 16QAM signal. For efficient implantation, and to facilitate integration with conventional digital signal processing (DSP) approaches, we independently compensate fiber nonlinearities after linear impairment equalization. Therefore this algorithm can be easily implemented in currently deployed transmission systems after using linear DSP. The proposed equalizer operates at one sample per symbol and requires only one computation step. The structure of the algorithm is based on a first-order perturbation model with quantized perturbation coefficients. Also, it does not require any prior calculation or detailed knowledge of the transmission system. We identified common symmetries between perturbation coefficients to avoid duplicate and unnecessary operations. In addition, we use only a few adaptive filter coefficients by grouping multiple nonlinear terms and dedicating only one adaptive nonlinear filter coefficient to each group. Finally, the complexity of the proposed algorithm is lower than previously studied nonlinear equalizers by more than one order of magnitude.
Highlights
To satisfy the ever-increasing capacity demand in optical fiber communications, both the spectral efficiency (SE) and the data-rate carried by each wavelength division multiplexed channel has to increase
We propose a novel nonlinear equalizer based on the first-order perturbation model with quantized perturbation coefficients
The gain of the last erbium-doped fiber amplifier (EDFA) is adjusted in order to compensate for losses occurring inside the recirculating loop, including switches, couplers and the band-pass filter
Summary
To satisfy the ever-increasing capacity demand in optical fiber communications, both the spectral efficiency (SE) and the data-rate carried by each wavelength division multiplexed channel has to increase. According to Shannon’s theory of linear communication systems, the channel capacity is logarithmically proportional to signal-to-noise ratio (SNR). The capacity can be increased by increasing the signal power. Because of fiber Kerr nonlinearities, there is an optimum launch power limit. Further increases in input signal power beyond the optimal power levels degrades transmission performance. Fiber nonlinearities are the major remaining impairments for the generation coherent optical fiber communication systems that limit the achievable transmission distance [1]
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