Single Coherent Detection of a 606-Gb/s CO-OFDM Signal with 32-QAM Subcarrier Modulation Using 4x 80-Gsamples/s ADCs

We report the detection of a record 606-Gb/s data rate (503-Gb/s excluding 20.5%-FECoverhead) by a single coherent receiver using four 80-Gsamples/s 32.5-GHz-bandwidth ADCs and reduced-guard-interval CO-OFDM with 32-QAM. Transmission of the signal with 7.76-b/s/Hz net intrachannel spectral efficiency is demonstrated. Introduction Enabled by the advances in high-speed analogto-digital converters (ADCs) and digital signal processors, digital coherent detection has been widely used for receiving high-speed optical signals beyond 100 Gb/s with high sensitivity 1,2 and powerful channel equalization capabilities . To overcome speed limitations of current electronics and opto-electronics, optical parallelization in the time3 or frequency4 domain has been used to generate Tb/s channels. In both cases, it is desirable to reduce the degree of optical parallelism as much as possible and generate and/or receive as high data rates as possible by all-electronic means, i.e., within a single detection. With 50-Gsamples/s (GS/s) ADCs and polarization-division-multiplexed (PDM) QPSK modulation, receivers with ~100 1,4 Gb/s per detection have been realized . Recently, 80-GS/s ADC front-ends with 30-GHz RF band-width have been used, together with single-carrier PDM-16-QAM modulation, to detect5 224-Gb/s With the additional use of optical time-division multiplexing (OTDM) at the transmitter, 456-Gb/s have been received in a single detection6. Using spectrally-efficient reduced-guard-interval (RGI) CO-OFDM with 16-QAM sub-carrier (SC) modulation, 224-Gb/s per detection was achieved with 50-GS/s ADCs7.