Patent ID: 6501883
Filing Date: 2002-12-31
Classification: G02B

Abstract:
A method for recording an optical grating along a waveguiding axis in a photosensitive medium, the method comprising:a) providing a phase mask proximate the photosensitive medium along the waveguiding axis; b) projecting a light beam through a portion of said phase mask to generate a light beam with a modulated intensity profile, said light beam with a modulated intensity profile impinging on the photosensitive medium to locally record therein a portion of the optical grating having a characteristic period; c) moving the light beam along the waveguiding axis of the photosensitive medium to successively record portions of the optical grating therealong; and d) concurrently to said moving of the light beam: i) moving the phase mask in a direction parallel to the moving of the light beam, said moving of the phase mask being adjusted relative to the moving of the light beam to locally tune the characteristic period of each portion of the optical grating; and ii) providing a curvature in said light beam along the direction of the waveguiding axis, said curvature having a wavefront radius of curvature at a phase mask plane selected to generally optimize an efficiency of the recording of the optical grating for said characteristic period.