Patent ID: 6198567
Filing Date: 2001-03-06
Classification: G02F

Abstract:
A variable optical attenuator comprising:a Faraday rotator comprising a ferromagnetic garnet film of a predetermined thickness t, said ferromagnetic film simultaneously exhibiting a first type of magnetic domain for rotating the plane of polarization for an optical signal passing therethrough in a first direction by a predetermined amount related to said garnet film thickness and a second type of magnetic domain for rotating the plane of polarization in a second, opposite direction the predetermined amount;an input single mode optical signal path;an output single mode optical signal path;a focusing/lensing arrangement disposed between the optical signal paths and said Faraday rotator for coupling an applied optical signal between said signal paths and said Faraday rotator; andan adjustable external magnetic field coupled to said Faraday rotator for controlling the presence of said first and second magnetic domains in said Faraday rotator such that the first and second magnetic domains may be either one of balanced and unbalanced and thereby control the degree of optical coupling between said input optical signal path and said output optical signal path.