Patent ID: 7177511
Filing Date: 2007-02-13
Classification: G02B

Abstract:
1. An optical fiber filter, comprising: an optical fiber; a pair of first coupling regions; and a phase-shift region; wherein the optical fiber comprises: wherein an optical signal can pass through the optical fiber, wherein the first coupling regions are formed in the optical fiber, at a predefined mutual distance, for producing power transfer between a first propagation mode of the optical signal and a second propagation mode of the optical signal, wherein the phase-shift region is defined by a section of the optical fiber, disposed between the first coupling regions, for producing a phase shift between the first and second propagation modes, and wherein refractive index profiles of the optical fiber in each of the first coupling regions are asymmetrical due to the presence of a cladding zone with a refractive index higher than a refractive index of the remainder of the cladding.