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Performance improvement of all-optical OFDM systems based on combining RZ coding with m-array QAM

J. K. HMOOD1,2, K. A. NOORDIN1, H. AHMAD3, S. W. HARUN1,3,*

Affiliation

  1. Department of Electrical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
  2. Department of Laser and Optoelectronic Engineering, University of Technology, 10066 Baghdad, Iraq
  3. Photonics Research Center, University of Malaya, 50603 Kuala Lumpur, Malaysia

Abstract

In this paper, we propose a new combination of RZ coding and m-array quadrature amplitude modulation (mQAM) to improve the performance of an all-optical OFDM system. Numerical simulation is used to evaluate the performance of the proposed all-optical OFDM system, which uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation. The system employs 29 subcarriers where each subcarrier is modulated with a symbol rate of 25Gsymbol/s. The results show that the nonlinear phase noise due to fiber nonlinearity is mitigated when the RZ-4QAM and RZ-16QAM format is employed. At the transmission distance of 550km, the error vector magnitude (EVM) reduces from 12.7% to 10.7% when the RZ-4QAM format is adopted instead of 4QAM. The required optical signal-to-noise ratios (OSNRs) to achieve a BER of 10−5 are reduced by about 1.9dB and 5.8dB when adopting the RZ-4QAM and RZ-16QAM all optical OFDM systems, as compared to the 4QAM and 16QAM all-optical OFDM systems..

Keywords

All-optical OFDM system, Fiber nonlinearity, m-array QAM, Phase noise, RZ-coding.

Submitted at: Nov. 17, 2014
Accepted at: Jan. 21, 2015

Citation

J. K. HMOOD, K. A. NOORDIN, H. AHMAD, S. W. HARUN, Performance improvement of all-optical OFDM systems based on combining RZ coding with m-array QAM, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 1-2, pp. 33-38 (2015)