Optical waveguide gratings having cladding for reduced short wavelength cladding mode loss

摘要

In accordance with the invention, an optical waveguide (34) comprising a longitudinally extending core (12) housing an optical grating (16) and a cladding layer (14) peripherally surrounding the core (12), is provided with an outer surface (36) of the cladding layer having one or more height perturbations. Each perturbation forming a smooth and connected taper, the height with respect to the core (12) varying by at least 0.1 times a Bragg wavelength of the grating (16) over a length of the taper equal to 0.5 times the grating's length whose lateral extent is less than about 100 Bragg wavelengths. The perturbations suppress cladding mode spectra and reduce short wavelength cladding mode loss.