Planar lightwave circuit for conditioning tunable laser output

A system for conditioning light output from a tunable laser designed to generate light at a target wavelength, the system comprising:

• a planar lightwave circuit (PLC) module comprising:
• a substrate;
• a primary waveguide embedded in said substrate, said primary waveguide having an input end for receiving light from the tunable laser and an output end for outputting said light;
• at least a first secondary waveguide embedded in said substrate, said first secondary waveguide receiving a first portion of said light from the tunable laser;
• and
• a filter having a passband centered on the target wavelength and coupled to an output of the first secondary waveguide to receive said first portion of light, wherein said filter is adapted to generate a filter output signal related to the intensity of said first portion of light in the passband centered on the target wavelength;
• and
• a processor for generating, based on said filter output signal, a control signal, to adjust the lasing wavelength of the tunable laser to achieve or maintain the target wavelength.