Abstract: Ridge and buried waveguide structures feature a plurality of trenches disposed proximate the waveguides in order to enhance confinement of an optical signal propagating within the waveguide are described. Additionally, an adiabatic transition region where the distance between trenches and waveguide is featured.

Abstract: The invention relates to a planar waveguide reflective diffraction grating for use in an optical device, such as a wavelength division multiplexer, providing an increased bandwidth over conventional planar waveguide reflection diffraction gratings while eliminating the polarization dependent loss (PDL) typically associated therewith. Accordingly, a low order (<3), high aspect ratio (>10) grating is provided with a very short side wall (less than the wavelength of the optical signal) for use with incident angles of less than 15°.

Abstract: The invention relates to a planar lightwave circuit including a pair of opposed concave reflective diffraction gratings sharing the same focal line, which separates first and second slab waveguide regions. The ends of input and output waveguides are positioned along the focal line for launching and receiving light directed by one or both of the diffraction gratings. The invention enables light within in a certain wavelength range to be launched from an input waveguide, directed by a single diffraction grating, and output waveguides, all within a single slab waveguide region, while light within another wavelength range will be directed from one diffraction grating to another for output waveguides in a different slab waveguide region.