A frequency-stabilised highly dense WDM comb generator

A novel and practicable technique for realising a bank of laser sources for generating an absolute-referenced frequency comb in the 1535-1565 nm window is described. The technique uses a WDM coupler-based wavelength meter that is periodically calibrated to an absolute frequency reference. The technique enables the frequency of a laser to be locked to any value within its tuneable range and is able to stabilise the frequencies of dense WDM carriers with arbitrary channel spacings. We demonstrate the use of this technique by generating a highly dense WDM comb of 8 transmitter lasers with 25 GHz channel separation based on the ITU grid. Channel stability and accuracy are better than 5% of the channel spacing.