Patent ID: 8693867

Claim:
A method for stabilising a plurality of output frequencies of a corresponding plurality of laser beams, having different central frequencies, including: directing the plurality of laser beams into an optical frequency to radio-frequency phase converter that defines a shared frequency reference, wherein the optical frequency to radio-frequency phase converter is a Mach-Zehnder Interferometer (MZI) with an arm length mismatch, and the shared frequency reference is defined by a value of the arm length mismatch; generating, using the MZI, a plurality of optical output signals corresponding to the plurality of laser beams and representative of frequency fluctuations between the respective central frequencies and the shared frequency reference; generating a plurality of electrical output signals, corresponding to the plurality of laser beams, using the plurality of optical signals; determining a plurality of radio-frequency phases corresponding to the plurality of electrical output signals; generating from the determined plurality of radio-frequency phases a corresponding plurality of feedback signals indicative of the respective frequency fluctuations; directing the plurality of feedback signals to a corresponding plurality of wavelength controllers of the laser beams to reduce the frequency fluctuations of the laser beams; modulating a portion of each laser beam in an arm of the MZI, based on a modulation signal, to generate a modulation in each optical output signal; and demodulating each electrical output signal to determine the radio-frequency phase of each electrical output signal.