Carrier sense using subcarrier-multiplexed signaling for optical frequency division multiple access

A novel subcarrier multiplexing based carrier sense technique called SCM-CS is proposed and is experimentally demonstrated. It can prevent the contention in optical frequency division multiple access networks that use an access protocol based on a fixed-wavelength transmitter and wavelength-tunable receiver. When two or more SCM signals on the same subcarrier frequency at different wavelengths simultaneously address the same destination node, SCM-CS detects the sum of the subcarrier frequencies by using RF heterodyne detection and denies the access. SCM-CS permits node access only if the carrier sense is negative which means that the destination node is idle. In the experiment, SCM-CS is successfully performed for 6.2 Mb/s SCM signals of the subcarrier frequency of 164 MHz with the frequency difference of the optical carriers up to 40 GHz.