Kim Byung Gon, Bae Sung Hyun, Kim Hoon, Chung Yun C
Opt Express. 2017 May 29;25(11):12152-12160. doi: 10.1364/OE.25.012152.
We propose and demonstrate a simple composite second-order (CSO) cancellation technique based on the digital signal processing (DSP) for the radio-over-fiber (RoF) transmission system implemented by using directly modulated lasers (DMLs). When the RoF transmission system is implemented by using DMLs, its performance could be limited by the CSO distortions caused by the interplay between the DML's chirp and fiber's chromatic dispersion. We present the theoretical analysis of these nonlinear distortions and show that they can be suppressed at the receiver by using a simple DSP. To verify the effectiveness of the proposed technique, we demonstrate the transmission of twenty-four 100-MHz filtered orthogonal frequency-division multiplexing (f-OFDM) signals in 64 quadrature amplitude modulation (QAM) format over 20 km of the standard single-mode fiber (SSMF). The results show that, by using the proposed technique, we can suppress the CSO distortion components by >10 dB and achieve the error-vector magnitude performance better than 6% even after the 20-km long SSMF transmission.
我们提出并演示了一种基于数字信号处理（DSP）的简单复合二阶（CSO）抵消技术，用于采用直接调制激光器（DML）实现的光纤无线（RoF）传输系统。当RoF传输系统采用DML实现时，其性能可能会受到DML啁啾与光纤色散相互作用引起的CSO失真的限制。我们对这些非线性失真进行了理论分析，并表明可以通过简单的DSP在接收机处对其进行抑制。为了验证所提技术的有效性，我们演示了在20 km标准单模光纤（SSMF）上传输24个采用64正交幅度调制（QAM）格式的100 MHz滤波正交频分复用（f-OFDM）信号。结果表明，通过使用所提技术，即使经过20 km长的SSMF传输，我们也可以将CSO失真分量抑制超过10 dB，并实现优于6%的误差矢量幅度性能。
