Wavelength control of multi-wavelength laser

The invention pertains to a photonic integrated circuit device (1) comprising a lasing cavity (2) for resonating at a plurality of discrete wavelengths and an optical feedback cavity (3) operably coupled to the lasing cavity via a front surface (5) of the lasing cavity. The optical feedback cavity comprises a reflective element (4) for reflecting light, at least partially, back into the lasing cavity (2) to form a resonant Fabry-Perot cavity between the front surface (5) and the reflective element (4). The optical feedback cavity (3) comprises a variable phase shifting element (6) adapted for receiving an input signal (7) to control a phase shift of light propagating in the optical feedback cavity. Preferably, the amount of light entering the lasing cavity (2) from the optical feedback cavity (3) is low enough to avoid dynamic instability of the lasing cavity. The reduction in light is preferably obtained using an attenuator.