Wavelength-stabilized semiconductor laser source

A semiconductor laser source comprising:

• (a) a semiconductor substrate;
• (b) an optical waveguide formed on the substrate and arranged so as to provide position-dependent optical gain or loss, for an optical signal that propagates along the waveguide within an operating wavelength range of the laser source, that varies according to a position-dependent level of electrical current density flowing into or out of the optical waveguide;
• (c) an optical reflector arranged on the substrate or waveguide so as to reflect, to propagate along the optical waveguide in a forward direction, at least a portion of an optical signal propagating along the waveguide in a rearward direction within the operating wavelength range;
• (d) an optical grating arranged on the substrate or waveguide so as to diffract, to propagate in the rearward direction along the waveguide toward the reflector, at least a portion of an optical signal propagating along the waveguide in the forward direction within the operating wavelength range, wherein the waveguide, reflector, and grating define a laser resonator arranged so that laser output from the laser resonator propagates (i) in the forward direction from the grating along the waveguide, (ii) in the rearward direction from the optical reflector, or (iii) in both directions, the laser output being characterized by a laser wavelength;
• (e) a first laser electrode positioned over a first segment, of length L1, of the waveguide between the reflector and the grating, the first laser electrode being arranged so as to enable a substantially constant first laser current I1 to flow through the first laser electrode into the first segment of the waveguide and produce optical gain therein;
• (f) a second laser electrode positioned over a second segment, of length L2, of the waveguide that includes at least a portion of the grating, the second laser electrode being arranged so as to enable a substantially constant second laser current I2 to flow through the second laser electrode into the second segment of the waveguide and produce optical gain therein;
• (g) an optical detector and a wavelength discriminator, with the wavelength discriminator being arranged so as to direct a wavelength-dependent fraction of the laser output onto the optical detector so as to generate therefrom a laser-wavelength electrical signal;
• and
• (h) a laser-control electrical circuit coupling the optical detector and one or both of the first or second laser electrodes in a feedback arrangement operative to control and stabilize the laser wavelength relative to a wavelength-dependent property of the wavelength discriminator, wherein the laser-control electrical circuit is arranged so as to (i) derive from the laser-wavelength electrical signal a wavelength-control current IWC, (ii) direct the first laser current I1 to flow through the first laser electrode, (iii) direct the second laser current I2 to flow through the second laser electrode, and (iv) direct the wavelength-control current IWC to flow through one or both of the first or second laser electrodes.