Crosstalk and Prefiltering in a Two-Channel ASK Heterodyne Detection System without the Effect of Laser Phase Noise.

Abstract

Coherent detection techniques in fiber optic communications have high potential for offering access to the vast transmission capacity of single mode fiber by the use of optical frequency division multiplexing (OFDM) [1]. However, one of the main issues concerning such multichannel OFDM systems is the crosstalk between the channels[2–4]. We have experimentally investigated the crosstalk penalty due to the image band interference in a two-channel ASK heterodyne system in which the effect of laser phase noise was negligible. We report: 1) the dependence of crosstalk penalty on the channel-separation-to-bit-rate ratio and on the optical power level of the image band, 2) the effect of electrical prefiltering on the crosstalk penalty, and 3) a demonstration of simultaneous broadcasting of two 45 Mb/s video/audio channels.