Patent ID: 6993221
Filing Date: 2006-01-31
Classification: G02B

Abstract:
1. A method for inducing a spatially modulated refractive index pattern in an optical waveguide, comprising: providing an optical waveguide; disposing a mask optically proximate the optical waveguide, the mask having a characteristic period; and, providing electromagnetic radiation on a surface of the mask, the electromagnetic radiation having a wavelength range, wherein the wavelength range of the electromagnetic radiation corresponds to the wavelength range from 10 nanometers to 15 microns, the electromagnetic radiation having a pulse duration of less than or equal to 500 picoseconds, the mask disposed to permit a portion of the electromagnetic radiation to interact with the mask and be incident on the optical waveguide, the interaction of the electromagnetic radiation with the mask for producing a spatial intensity modulation pattern within the optical waveguide, the electromagnetic radiation incident on the optical waveguide being sufficiently intense to cause a permanent change in an index of refraction of the optical waveguide, the electromagnetic radiation interacting with the surface of the mask having a sufficiently low intensity to not significantly alter produced spatial intensity modulation properties of the mask, the mask disposed relative to the optical waveguide such that a portion of the provided electromagnetic radiation produces more than two diffracted orders thereby resulting in a multiple beam interference field within the optical waveguide providing a field pattern thereby inducing a permanent index change in the optical waveguide, the permanent index change in the waveguide having a characteristic period greater than half that of the mask.