Chung Hwan Seok, Chang Sun Hyok, Kim Kwangjoon
Optical Internet Research Department, Electronics and Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejon, 305-700, South Korea.
Opt Express. 2011 Dec 12;19(26):B702-9. doi: 10.1364/OE.19.00B702.
We demonstrate a mitigation of fiber nonlinearity based on μ-law companding transform in coherent optical OFDM transmissions. High peak-to-average power ratio (PAPR) increases fiber nonlinear impairments caused by the Kerr effect in optical fiber. The μ-law companding modifies amplitude profile of OFDM signal with time domain signal processing, which reduces high PAPR of OFDM signal. The effects of companding parameter on noise enhancement and PAPR variation are presented. The impacts of companding transform on system performances are evaluated in a single polarization system as well as polarization multiplexed system. The resolution of analog-to-digital converter (ADC), dispersion map of transmission link, and launch power tolerance are also considered. The results of bit-error-rate (BER) measurements show that the μ-law companding improves OSNR margin over 5.5 dB after transmission of 1,040 km over SMF.
我们展示了在相干光正交频分复用（OFDM）传输中基于μ律压扩变换对光纤非线性的缓解。高峰均功率比（PAPR）会增加光纤中克尔效应引起的光纤非线性损伤。μ律压扩通过时域信号处理修改OFDM信号的幅度分布，从而降低OFDM信号的高PAPR。给出了压扩参数对噪声增强和PAPR变化的影响。在单偏振系统以及偏振复用系统中评估了压扩变换对系统性能的影响。还考虑了模数转换器（ADC）的分辨率、传输链路的色散图和发射功率容限。误码率（BER）测量结果表明，在单模光纤（SMF）上传输1040公里后，μ律压扩将光信噪比（OSNR）余量提高了超过5.5分贝。
