Coherent optical orthogonal frequency division multiplexing

Introduction: Orthogonal frequency division multiplexing (OFDM) has been extensively investigated to combat RF microwave multipath fading, and has been widely implemented in various digital communication standards such as wireless local area network standards (WIFI IEEE 802.11a) [1]. In this Letter, we propose an optical equivalent of the RF OFDM called coherent optical OFDM (CO-OFDM) to combat dispersion in fibre media. We show that with CO-OFDM the optical-signal-to-noise ratio (OSNR) penalty can be maintained below 2 dB for 3000 km transmission through standard-singlemode fibre (SSMF) without chromatic dispersion compensation. As such, CO-OFDM may be an alternative solution for electrical predistortion [2], but with the additional advantage that the optical signal can be dropped at any point within 3000 km.