Wideband Parametric Frequency Comb as Coherent Optical Carrier

We report the first use of the CW-seeded parametric comb as a multiwavelength source for coherent channel transmitters. The new comb source relies on a multistage parametric mixer design seeded by a single kilohertz-linewidth master laser. The resultant frequency comb provides more than 120 tones in a 100-nm-wide continuous band, all possessing kilohertz-scale linewidth inherited from the master laser. The applicability of the new comb source as a coherent channel carrier was quantified by error-vector magnitude and bit-error rate metrics of individual spectral lines modulated by QPSK signaling. The performance of the new source exceeded that of the standard tunable coherent transmitter while providing a qualitatively lower frequency uncertainty and drift.