Patent ID: 6934313

Claim:
A method comprising: forming a resonant cavity of a laser device, by forming a laser waveguide in a laser gain medium chip having a rear facet, wherein a segment of the laser waveguide is formed of a composite structure including a component having a negative thermo-optic refraction index coefficient; forming an intracavity waveguide including a plurality of gratings; optically coupling the laser waveguide to the intracavity waveguide via an optical coupling segment to form the resonant cavity, reflective ends of the resonant cavity defined by the rear facet of the gain medium chip and the grating in the intracavity waveguide, the resonant cavity characterized by a round trip optical path length defining a free spectral range between adjacent longitudinal mode frequencies of said laser device, wherein the segment of the laser waveguide formed of the composite structure is configured such that a round trip optical path length of the resonant cavity is substantially athermal; operating the laser device by providing an electrical input to the gain medium chip to produce an optical emission comprising a plurality of photons that resonate within the resonant cavity to produce an optical output; monitoring the optical output to determine a free spectral range of the laser device; and modifying an effective refractive index of at least a portion of the intracavity waveguide until the free spectral range substantially equals a predetermined rational fraction of a specified frequency channel spacing over a portion of an operating frequency band.