Homodyne 24xx32-QAM Superchannel Receiver Enabled by All-Optical Comb Regeneration Using Brillouin Amplification

We demonstrate and characterize an all-optical self-homodyne (SH) frequency superchannel enabled by comb regeneration at the receiver. In order to generate the frequency superchannel, we use a frequency comb with 26 carriers spaced by 25 GHz at the transmitter, from which 24 carriers are modulated as polarization-multiplexing 32 quadrature-amplitude modulation (PM-32 QAM). The two central carriers remain unmodulated in order to regenerate the frequency comb at the receiver. In order to regenerate the frequency comb with high fidelity,the unmodulated carriers are filtered with an about 20 MHz optical filter based on Brillouin amplification before regenerating the optical comb using a parametric mixer. The carriers from the regenerated comb are used as local oscillator for SH detection. We demonstrate that all 24 carriers can be detected with an optical signal-to-noise ratio (OSNR) penalty lower than 2.5 dB in a back-to-back scenario. We also demonstrate that whole superchannel can be transmitted through 120 km of single-mode fiber (SMF) and detect all the carrier with bit-error rate (BER) below 0.02.