Patent ID: 6816300
Filing Date: 2004-11-09
Classification: G02B,G02F,H01F

Abstract:
An optical device comprising:a Faraday rotator made of a bismuth substituted rare earth iron garnet single crystal film having a Faraday rotation of 45 degrees; and permanent magnets arranged beside said Faraday rotator to define two or more than two areas of a single domain structure in said Faraday rotator; wherein adjacent areas are magnetized in opposite directions to cause polarization planes of light beams passing through the adjacent areas to rotate in opposite directions, and the optical device satisfies the relation expressed by equation (1) Hs/Br/DH>&Dgr;D/2>0â€ƒâ€ƒ(1) where Hs (Oe) is a saturation magnetic field of the bismuth substituted rare earth iron garnet single crystal film, DH (cmâˆ’1) is a rate of change in magnetic field in the proximity to a boundary between the adjacent areas, Br (Gauss) is a residual flux density of said permanent magnets, and &Dgr;D is a distance between the two light beams.