Abstract

Coherent optical receivers with electronic dispersion compensation (EDC) become ubiquitous for high-capacity and long-distance transmissions. However, their performance can be decimated by equalization-enhanced phase noise (EEPN). The existing reports have shown some unique features that deserve further studies, especially for high-order modulation formats. In this paper, we firstly show that the intra-symbol EEPN is dominated by the phase noise. Therefore, the probability density function (PDF) due to intra-symbol EEPN and inter-symbol EEPN are quite different. We derive the variances of EEPN-induced phase and amplitude noise for QPSK signals, and fully explain the elliptical PDF. Secondly, we show that the intra-symbol EEPN is scaled with the power of the different modulus, but the inter-symbol one, the average power of the constellation. Subsequently, we elucidate that for higher-order constellations with multiple moduli, the total EEPN, the EEPN-induced phase noise and amplitude noise, all distribute differently on the different moduli. Finally, we analyze the EEPN after the practical carrier phase recovery algorithms, also with a closed-form prediction. Our analysis of EEPN is readily extended to arbitrary modulation formats.

Experimental investigation of the equalization-enhanced phase noise in long haul 56 Gbaud DP-QPSK systems

Qunbi Zhuge, Xian Xu, Ziad A. El-Sahn, Mohammad E. Mousa-Pasandi, Mohamed Morsy-Osman, Mathieu Chagnon, Meng Qiu, and David V. Plant
Opt. Express 20(13) 13841-13846 (2012)

Equalization-enhanced phase noise for 100Gb/s transmission and beyond with coherent detection

Alan Pak Tao Lau, Thomas Shun Rong Shen, William Shieh, and Keang-Po Ho
Opt. Express 18(16) 17239-17251 (2010)

Equalization-enhanced phase noise induced timing jitter

Keang-Po Ho, Alan Pak Tao Lau, and William Shieh
Opt. Lett. 36(4) 585-587 (2011)

Study of EEPN mitigation using modified RF pilot and Viterbi-Viterbi based phase noise compensation

Gunnar Jacobsen, Tianhua Xu, Sergei Popov, and Sergey Sergeyev
Opt. Express 21(10) 12351-12362 (2013)

Equalization-enhanced phase noise for coherent-detection systems using electronic digital signal processing

William Shieh and Keang-Po Ho
Opt. Express 16(20) 15718-15727 (2008)