Nonlinear effect mitigation based on PAPR reduction using electronic pre-distortion technique in direct-detection optical OFDM system

Abstract

The nonlinear effect induced by the Mach–Zehnder modulator (MZM) and optical self-phase modulation (SPM) in the presence of high peak-to-average power ratio (PAPR) is investigated theoretically. We theoretically and experimentally investigate the direct-detection optical orthogonal frequency-division multiplexing (DD-OOFDM) system with an electronic pre-distortion technique of companding transform (CT) to reduce the peak-to-average power ratio (PAPR) of OFDM signals and improve the receiver sensitivity. Experimental results show that the PAPR reduction can reach about 3dB when the complementary cumulative distribution function is 1×10−4, which means the number of random OFDM signals is 1×104, and the receiver sensitivity is improved by 0.7, 1.7, and 2.4dB for the launch power of 2, 6 and 10dBm, respectively, at the BER of 1×10−4 after transmission over 100-km single-mode fiber with the μ of 2. It shows that the PAPR reduction can mitigate not only the nonlinearity of MZM, but also the nonlinear phase noise in the fiber link when the optical power into fiber is high.