WDM Orthogonal Subcarrier Multiplexing Based on Mode-Locked Lasers

The (de)modulation of broadband orthogonal subchannels relying on all-analogue signal processing potentially achieves high-capacity orthogonal subcarrier multiplexing (OSCM) electro-optical transceivers with low power consumption and latency. Overall transmission rates can be multiplied by employing wavelength division multiplexing (WDM) technology. Mode-locked lasers (MLL) are relevant optical frequency combs, as they produce a high number of comb tones while presenting a small footprint and low power consumption. Unlike baseband transmission, the use of high-frequency subchannels in OSCM systems overcomes the high relative intensity noise that MLL comb tones present at low frequencies. This paper reports a direct-detection real-time all-analogue WDM/OSCM experiment that emulates a 432 Gbit/s (20 × 21.6 Gbit/s) electro-optical transceiver. The 20 optical carriers were generated by a state-of-the-art quantum-dash MLL. The net data rate after considering forward error correction overheads is still higher than 400 Gbit/s. This is the highest capacity achieved in real-time broadband all-analogue WDM/OSCM links to date.