Integrated optic wavemeter

An integrated optic wavemeter for producing a signal indicative of a wavelength of an optical input signal, the wavemeter comprising:

• a waveguide structure formed in a substrate, the waveguide structure including a signal waveguide and a reference waveguide, each waveguide having an optical path length, and means for coupling the optical input signal into the signal and reference waveguides;
• means for varying the optical path length of the signal waveguide with respect to the optical path length of the reference waveguide in response to a control signal;
• a detection system coupled to receive optical signals from the signal and reference waveguides and including means for producing a feedback signal having a characteristic that is a function of an optical path length difference between the signal and reference waveguides, and of the wavelength of the optical input signal;
• and
• a control system coupled to receive the feedback signal and including means for producing the control signal and coupling the control signal to the means for varying the optical path length, the control signal being produced such that the resulting variation of the optical path length drives the feedback signal characteristic towards a predetermined value, whereby the control signal provides a measure of the wavelength of the optical input signal.