Ring resonator with wavelength selectivity

An optical device, comprising:

• waveguides configured to guide light signals, the waveguides including an input waveguide and one or more loop waveguides,
• one of the loop waveguides being a primary loop waveguide that is optically coupled with the input waveguide at a coupled wavelength of light, the optical coupling being such that light guided in the input waveguide and having the coupled wavelength is coupled into the primary loop waveguide,
• a tuner configured to tune the wavelength at which the light is optically coupled from the input waveguide into the primary loop waveguide;
• one or more light detectors that each provides an output indicating an intensity of light guided on one of the one or more loop waveguides, one of the one or more light detectors is a first light detector configured to provide an output indicating the intensity of the light guided on a second one of the loop wavegides, the second loop waveguide being different from the primary loop waveguide;
• and
• electronics that tune the tuner in response to the output from the first light detector.