Patent ID: 7830938

Claim:
A laser diode comprising: a layer stack of semiconductor material, including, in succession: a first cladding layer, for confining an optical mode; a first waveguide layer, for propagating the optical mode; a mode-splitting layer, for splitting the optical mode to produce an intensity maximum and a shoulder; a second waveguide layer, for propagating the optical mode; an active layer, for generating the optical mode; a third waveguide layer, for propagating the optical mode; and a second cladding layer, for confining the optical mode; wherein the first waveguide layer, the mode-splitting layer, the second waveguide layer, and the third waveguide layer have respective thicknesses that are selected to position the intensity maximum in the active layer and the shoulder in the first waveguide layer; wherein the first waveguide layer, the second waveguide layer, and the third waveguide layer have a substantially equal refractive index; and wherein the first cladding layer, the mode-splitting layer, and the second cladding layer have respective refractive indices that are each less than the refractive index of the first waveguide layer, the second waveguide layer, and the third waveguide layer.