PAPR Reduction and Nonlinearity Mitigation of Optical Digital Subcarrier Multiplexing Systems With a Silicon Photonics Transmitter

作者：Jinsong Zhang, Essam Berikaa, R. Gutiérrez-Castrejón, Md Samiul Alam, Fabio Cavaliere, Stéphane Lessard, Zixian Wei, Weijia Li, David V. Plant · 发表于：Journal of Lightwave Technology · 年份：2023 · DOI：10.1109/jlt.2023.3296648 · 被引用次数：11 · 研究领域：Optical Network Technologies、PAPR reduction in OFDM、Advanced Photonic Communication Systems

We propose two low-complexity digital signal processing (DSP) techniques to improve the system performance of digital subcarrier multiplexing (DSCM) optical transmission system with a silicon photonics transmitter. We first analyze the impacts of various transmitter parameters on the system performance of the single carrier system versus the DSCM system. We show quantitatively that the DSCM system suffers from a high peak-to-average power ratio (PAPR) and nonlinear transfer functions that cannot be easily compensated for. Furthermore, using a high-driving-voltage silicon photonics modulator exacerbates this penalty at the transmitter. To combat the performance degradation caused by nonideal transmitters, we propose and demonstrate the functionality of an encoding scheme based on the fast Fourier transform (FFT) to decrease the PAPR of the transmitted DSCM signals. Then a simple and effective pre-mapping technique is proposed to compensate for the nonlinearity from the transmitter. After developing the theory of our proposed approach, both DSP blocks are verified with coherent optical transmission simulations and experiments. Using a 64 GBd 4-bit/s/Hz DSCM signal containing 8 subcarriers transmitted over 43.2 km of standard single-mode fiber (SSMF), the FFT encoding achieves a gain of 3.458 dB in terms of link loss, and the pre-mapping achieves a gain of 0.486 dB when compared to the raw DSCM system, at the HD-FEC bit error rate (BER) threshold of 3.8e-3. We also tested the pe...