Wavelength locker

A wavelength monitor comprising:

• a laser source for generating a laser signal;
• a tap for tapping a portion of the laser signal forming a test signal;
• a splitter for splitting the test signal into a plurality of test beams;
• a combination comb filter comprising a plurality of comb filters, each for receiving a respective one of the test beams, each comb filter including a different FSR, the plurality of comb filters comprising a first filter comprising a first FSR and a first largest detection wavelength range, a second filter comprising a second FSR and a second intermediate detection wavelength range, and a third filter comprising a third FSR and a third smallest detection wavelength range;
• at least one photodetector for measuring output from each comb filter;
• a phase tuning section for each comb filter for tuning each of the plurality of comb filters;
• and
• a controller for controlling the phase tuning section of each comb filter to generate a maximum or minimum output in a corresponding one of the least one photodetector indicative of a wavelength of the test signal;
• wherein the controller is configured to tune the first filter to determine that the wavelength of the test signal is within the first largest detection wavelength range;
• tune the second filter to determine that the wavelength of the test signal is within the second intermediate detection wavelength range within the first largest detection wavelength range;
• and tune the third filter to determine that the wavelength of the test signal is within the third smallest detection wavelength range within the second intermediate detection wavelength range;
• and
• wherein the controller is configured to determine the wavelength of the test signal using values of pre-calibrated electrical signals used by each phase tuning section to tune each of the plurality of comb filters;
• and
• wherein the controller is configured to tune the laser source based on the wavelength of the test signal.