Title :
Theoretical and Experimental Investigations of Direct-Detected RF-Tone-Assisted Optical OFDM Systems
Author :
Peng, Wei-Ren ; Wu, Xiaoxia ; Arbab, Vahid R. ; Feng, Kai-Ming ; Shamee, Bishara ; Christen, Louis C. ; Yang, Jeng-Yuan ; Willner, Alan E. ; Chi, Sien
Author_Institution :
Dept. of Photonics, Nat. Chiao Tung Univ., Hsinchu
fDate :
5/15/2009 12:00:00 AM
Abstract :
In this paper, we propose and experimentally demonstrate a radio frequency (RF)-tone-assisted optical orthogonal frequency-division multiplexing (OFDM) transmission. By inserting an RF tone at the edge of the signal band and biasing the Mach-Zehnder modulator (MZM) at the null point, the proposed system has a better sensitivity and chromatic dispersion (CD) tolerance compared to the previous intensity-modulated single-sideband OFDM (SSB-OFDM). We show analytically that the majority of the linear channel impairments, such as the transmitter, CD, optical filtering, and receiver, can be compensated for by a simple zero-forcing equalizer. Besides, the optimum value of the important parameter, carrier-to-signal-power ratio (CSPR), is analytically obtained and supported via the experimental results. We also observe that the relatively worse sensitivity of the previous SSB-OFDM can be attributed to the limited CSPR. We experimentally demonstrate a 10-Gb/s, 8 quadrature-amplitude modulation (QAM) RF-tone-assisted OFDM transmission, and show that our system has a ~ 5-dB better sensitivity compared to the previous intensity-modulated SSB-OFDM and exhibits a negligible transmission penalty after 260-km uncompensated standard single-mode fiber (SSMF).
Keywords :
OFDM modulation; equalisers; optical fibre communication; optical filters; quadrature amplitude modulation; Mach-Zehnder modulator; carrier-to-signal-power ratio; chromatic dispersion tolerance; direct-detected RF-tone-assisted optical OFDM systems; intensity-modulated single-sideband OFDM; linear channel impairments; optical filtering; optical orthogonal frequency-division multiplexing transmission; quadrature-amplitude modulation; radio frequency tone-assisted transmission; uncompensated standard single-mode fiber; zero-forcing equalizer; Direct detection; optical fiber communication; optical modulation; orthogonal frequency-division multiplexing (OFDM);
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2008.2012172