Ring laser optical system

A method for generating an optical output signal on an output waveguide, the method comprising:

• providing a first control signal to a ring laser to generate a ring laser optical signal;
• providing a first portion of the ring laser optical signal on the output waveguide via a first evanescent coupling;
• providing a second portion of the ring laser optical signal on a local waveguide via a second evanescent coupling;
• receiving a feedback signal associated with an intensity of the first portion of the ring laser optical signal from a receiver photodetector that is coupled to the output waveguide;
• and
• controlling an effective distance between the second evanescent coupling and a reflector at a first end of the local waveguide to provide constructive interference of the second portion of the ring laser optical signal with the ring laser optical signal at the second evanescent coupling to provide unidirectional lasing of the ring laser optical signal in the ring laser;
• wherein controlling the effective distance between the second evanescent coupling and the reflector comprises controlling a phase of the second portion of the ring laser optical signal using a phase tuning element through which the local waveguide passes.

An optical system comprising:

• an output waveguide to propagate an optical output signal;
• and
• a plurality of ring laser systems, each of the plurality of ring laser systems comprising:
• a local waveguide;
• a ring laser to generate a ring laser optical signal, the ring laser being evanescently coupled to the output waveguide to provide a first portion of the ring laser optical signal as a portion of the optical output signal, and being evanescently coupled to the local waveguide at a coupling location to provide a second portion of the ring laser optical signal on the local waveguide;
• a phase tuning element through which the local waveguide passes and located between the coupling location and a reflector at a first end of the local waveguide, the phase tuning element to adjust a refractive index of a portion of the local waveguide in response to a control signal to control a phase of the second portion of the ring laser optical signal to provide constructive interference with the ring laser optical signal at the coupling location to facilitate unidirectional lasing of the ring laser;
• and
• a photodetector at a second end of the local waveguide to monitor an optical power of the second portion of the ring laser optical signal to indicate whether the ring laser is operational and providing the unidirectional lasing.