WAVEGUIDE STRUCTURE WITH ASYMMETRICAL GRATING AND METHOD FOR PRODUCTION THEREOF

摘要

A novel optical waveguide structure and a method for production thereof are described. The optical waveguide structure includes a single mode core constituted by a radiation amplifying medium, a multimode inner cladding surrounding the core, a multimode outer cladding surrounding the inner cladding, and an asymmetrical grating constituted by perturbations in the refractive index in the inner cladding and having a non-uniform transverse refractive index profile formed at least in a portion of the inner cladding. The asymmetrical grating is operable to reflect a pump multimode radiation propagating in the inner cladding and to couple this pump multimode radiation into the single mode core. The method for producing the optical waveguide structure includes providing a fiber waveguide structure having a single mode core, a multimode inner cladding surrounding the core, and a multimode outer cladding surrounding the inner cladding; obtaining an asymmetrical property of an asymmetrical grating by defining a number of asymmetrical gratings and a respective position thereof within the inner cladding; and exposing the multimode inner cladding to an interference pattern created by an illumination source.