Abstract: In the manufacture of optical devices such as, e.g., optical communications assemblies and optical gyroscopes, low-loss substrate-supported optical waveguides are desired. Such waveguides can be obtained by patterning a layer of deposited waveguide material and, in the interest of minimizing loss as may be due to processing-induced surface roughness, waveguides as patterned preferably undergo a heat treatment which results in surface smoothing and in rounding of the waveguide cross section. Furthermore, in the interest of avoiding re-entrant corners between substrate and waveguide, a wetting layer may be applied to the waveguide prior to heat treatment.

Abstract: Highly frequency-selective reflectivity is realized in an optical device including a waveguide and an evanescent-field coupled grating resonator cavity. The device may include a light source and serve as a low-chirp, narrow-linewidth communications laser for use, e.g., for transmission over a fiber having non-negligible dispersion and also in wavelength-multiplexed coherent systems.

Abstract: A buried heterostructure laser which obtains lowest mode operation by larger differences in loss between the lowest and higher order modes is described. The loss is achieved by interface scattering between the mesa and the burying layer. The scattering losses increases with refractive index discontinuity, interface roughness and decreasing mesa width. Stabilization results because scattering losses increase rapidly with the order of the transverse modes.

Abstract: A buried heterostructure laser which obtains lowest mode operation by larger differences in loss between the lowest and higher order modes is described. The loss is achieved by interface scattering between the mesa and the burying layer. The scattering losses increase with refractive index discontinuity, interface roughness and decreasing mesa width. Stabilization results because scattering losses increase rapidly with the order of the transverse modes.