High Speed Optical Coherent Transmission System Using Narrowband FM Subcarrier Multiplexing

Abstract

AbstractA high speed optical coherent transmission System using Narrowband Frequency Modulation (NBFM) subcarrier multiplexing (SCM) has been introduced where the FM modulated optical signal for MPSK digital data is transmitted by a single mode fiber. At the receiver, a photodiode (PD) generates the electrical signal including N channel SCM signals and the optical intermediate frequency (IF) from the coupler. The electrical signal from the BPF output is FM demodulated and then divided into the N SCM data.We have analyzed the variance of Gaussian noise at the FM discriminator output for four adjacent sucarrier channels which are degraded by 10.1, 12.0, and 14.5 [nW/Hz] as the subcarrier frequency is increased by 0.5 GHz, respectively. The caculation results of BERs for the M-ary PSK modulators, BPSK, QPSK, 8-PSK, and 16-PSK schemes that shows the SNR differences between the modulation schemes are 1.9, 2.1. 2.3 dB at BER = 109, as the subcarrier frequency is increased by 0.5 GHz, respectively.KeywordsSubcarrier MultiplexingNarrowband Frequency ModulationOptical Coherent Transmission