Comb-Based 16-QAM Transmitter Spanning the C and L Bands

A multiwavelength source for optical transmitters delivers narrow-linewidth carrriers with 100-GHz spacing spanning the C and L bands. The phase-locked carriers are derived from a single, 3-kHz linewidth source, and a multistage parametric mixer. Bit-error rate measurements for a 20-GBd 16-QAM transmitter based on this source are reported.