Redyuk A, Stephens M F C, Doran N J
Opt Express. 2015 Oct 19;23(21):27240-9. doi: 10.1364/OE.23.027240.
We perform an extensive numerical analysis of Raman-Assisted Fibre Optical Parametric Amplifiers (RA-FOPA) in the context of WDM QPSK signal amplification. A detailed comparison of the conventional FOPA and RA-FOPA is reported and the important advantages offered by the Raman pumping are clarified. We assess the impact of pump power ratios, channel count, and highly nonlinear fibre (HNLF) length on crosstalk levels at different amplifier gains. We show that for a fixed 200 m HNLF length, maximum crosstalk can be reduced by up to 7 dB when amplifying 10x58Gb/s QPSK signals at 20 dB net-gain using a Raman pump of 37 dBm and parametric pump of 28.5 dBm in comparison to a standard single-pump FOPA using 33.4 dBm pump power. It is shown that a significant reduction in four-wave mixing crosstalk is also obtained by reducing the highly nonlinear fibre interaction length. The trend is shown to be generally valid for different net-gain conditions and channel grid size. Crosstalk levels are additionally shown to strongly depend on the Raman/parametric pump power ratio, with a reduction in crosstalk seen for increased Raman pump power contribution.
我们在波分复用正交相移键控（WDM QPSK）信号放大的背景下，对拉曼辅助光纤光学参量放大器（RA - FOPA）进行了广泛的数值分析。报告了传统FOPA和RA - FOPA的详细比较，并阐明了拉曼泵浦所具有的重要优势。我们评估了泵浦功率比、通道数以及高非线性光纤（HNLF）长度对不同放大器增益下串扰水平的影响。我们表明，对于固定的200 m HNLF长度，在使用37 dBm的拉曼泵浦和28.5 dBm的参量泵浦以20 dB净增益放大10×58 Gb/s QPSK信号时，与使用33.4 dBm泵浦功率的标准单泵FOPA相比，最大串扰可降低多达7 dB。结果表明，通过缩短高非线性光纤相互作用长度，四波混频串扰也能显著降低。对于不同的净增益条件和通道网格尺寸，该趋势通常是有效的。此外，串扰水平强烈依赖于拉曼/参量泵浦功率比，随着拉曼泵浦功率贡献的增加，串扰会降低。
