Wavelength control of multi-wavelength laser

A photonic integrated circuit device comprising:

• a lasing cavity for resonating at a plurality of discrete wavelengths;
• and
• an optical feedback cavity operably coupled to the lasing cavity via a front surface of the lasing cavity,
• said optical feedback cavity comprising a reflective element for reflecting light, at least partially, back into the lasing cavity to form a resonant Fabry-Perot cavity between the front surface and the reflective element,
• said optical feedback cavity further comprising a variable phase shifting element adapted for receiving an input signal to control a phase shift of light propagating in the optical feedback cavity,
• wherein the photonic integrated circuit device is configured such that at least a subset of the plurality of discrete wavelengths of light rays that are reflected back by the reflective element that are supported by the lasing cavity are not in phase and do not resonate together in the lasing cavity, and
• wherein the photonic integrated circuit device is configured to superpose the light rays reflected back by the reflective element onto forward propagating light rays inside the laser cavity which causes one mode to resonate and be boosted.