Laser system with active wavelength control

A wavelength division multiplexing (WDM) optical source, comprising:

• a support;
• a first chip comprising a tunable laser array, wherein the first chip is mounted to the support;
• a second chip comprising an optical multiplexer, wherein the second chip is mounted to the support, wherein the tunable laser array is optically coupled to the optical multiplexer;
• and
• a controller coupled to the first and second chips, wherein the controller is configured to:
• perform coarse spectral alignment between the tunable laser array and the optical multiplexer, wherein performing the coarse spectral alignment comprises:
• setting a temperature at which the optical multiplexer operates by controlling a first thermo-electric cooler (TEC) thermally coupled to the optical multiplexer,
• applying a collective bias to the tunable laser array, and
• setting a temperature at which the tunable laser array operates by controlling a second TEC thermally coupled to the tunable laser array, and
• subsequent to performing the coarse spectral alignment, perform fine spectral alignment between the tunable laser array and the optical multiplexer.

A method for controlling a wavelength division multiplexing (WDM) optical source, the method comprising:

• performing coarse spectral alignment between a tunable laser array and an optical multiplexer, wherein performing the coarse spectral alignment comprises:
• setting a temperature at which the optical multiplexer operates using a first signal generated by a first photodetector array, coupled to the tunable laser array, and a second signal generated by a second photodetector array, coupled to the optical multiplexer,
• applying a collective bias to the tunable laser array, and
• setting a temperature at which the tunable laser array operates;
• and
• subsequent to performing the coarse spectral alignment, performing fine spectral alignment between the tunable laser array and the optical multiplexer, wherein performing the fine spectral alignment comprises individually varying biases applied to tunable lasers of the tunable laser array from the collective bias.