Hybrid optical frequency comb source for 9.6 Tbit/s DWDM transmission over standard fiber

Abstract For meeting the increasing demand of ultra-fast data trans-receiver systems in hundreds of terabits per second, the realization of dense wavelength-division multiplexing (DWDM) technology is a key enabling technology. Nevertheless, existing DWDM implementation technologies depend on numerous discrete laser sources for optical bandwidth utilization, resulting in increased cost, complexity, and reduced efficiency. As an alternative, Optical Frequency Comb (OFC) offer a spectrally broad, and tunable multichannel source suitable for terabit-scale transmissions. In this work, a hybrid OFC generation technique combining electro-optic modulation and self-gain modulation in a semiconductor optical amplifier is proposed to expand a narrowband comb. The proposed approach generates a 4.8 THz-wide OFC with 30 GHz channel spacing. The proposed comb is validated by modulating all 160 comb lines with 60 Gbps DP-DQPSK signals and transmitting them over 94.4 km of fiber while maintaining a minimum Q-factor of 19 dB at the receiver. This hybrid approach addresses the limitations of electro-optic only systems (restricted bandwidth) and nonlinear techniques (poor spectral flatness), enabling a single seed laser for massively parallel data channels.