Patent ID: 8259767

Claim:
A semiconductor laser array device-comprising: (a) a quantum cascade laser structure comprising a core; (b) an optical confinement structure comprising at least one layer of optical confinement material above the quantum cascade laser structure and at least one layer of optical confinement material below the quantum cascade laser structure; (c) a cladding structure comprising at least one layer of cladding material above the optical confinement structure and at least one layer of cladding material below the optical confinement structure; and (d) a plurality of laterally-spaced trench regions extending transversely, partially into the quantum cascade laser structure; wherein each trench region comprises a lower trench layer comprising a semi-insulating material and an upper trench layer comprising a material having a refractive index that is higher than the refractive index of the semi-insulating material; and further wherein the trench regions define interelement regions separated by element regions in the laser array device; the laser array device characterized in that the effective refractive index of the fundamental transverse mode supported in the interelement regions is higher than the effective refractive index of the fundamental transverse mode supported in the element regions, and further characterized in that the laser array device is designed to produce an in-phase array mode meeting the lateral resonance condition in which there is strong coupling via leaky waves between all of the element regions.