Influence of EEPN and P2A noise with CD pre- and post-compensation in optical SSB transmission and Kramers-Kronig receiver system.

ABSTRACT

We present a comparative study of equalization-enhanced phase noise (EEPN) and phase to amplitude (P2A) noise with chromatic dispersion (CD) pre- and post-compensation in single side-band (SSB) transmission and direct-detection (DD) systems, respectively. We analyze the interplay of laser phase noise and fiber dispersion on an optical SSB Nyquist shaped four-level pulse amplitude modulation (PAM-4) signal in a Kramers-Kronig (KK) receiver. Our main results show that the EEPN in a DD-KK receiver dominates the system noise with the relaxed signal-to-noise ratio (SNR). The P2A noise in CD post-compensation scheme is relaxed due to the complex filed recovery with KK receiver. The numerical simulations are implemented to illustrate the interplay of laser linewidth and fiber dispersion in both CD pre- and post-compensation scenarios. Compared with CD pre-compensation, 3-dB reduction of power spectral density (PSD) of P2A noise at the peak is alleviated with CD post-compensation. The laser linewidth has ~1 MHz release with CD post-compensation for a 56-Gbaud PAM-4 signal over 100-km standard single-mode fiber (SSMF) transmission.