| 主权项 |
1. A multi-pass Faraday rotator comprising:
an optical input port; an optical output port; a Faraday optic comprising a block of optically transparent material capable of Faraday effect rotation, said Faraday optic longitudinally disposed on a beam path between said optical input port and said optical output port, said block having two optical faces substantially normal to said beam path, said beam path making at least two passes between said optical faces and thereby forming a beam path plane; a permanent magnet structure for producing an intense, unidirectional magnetic field in said Faraday optic in order to induce rotation of the plane of polarization of optical radiation of the beam, said permanent magnet structure including at least six permanent magnets each magnetized along their magnetization axis; said magnets being attached to outer pole plates at a distal plane surface from the beam path plane and disposed in mirror image magnet sets on opposite sides of the beam path plane with magnets of a first magnet set being disposed generally with like-type poles in transverse registration with the magnets of a second magnet set; said magnet sets formed of a central block of permanent magnet material with magnetization oriented substantially parallel to the beam path plane and to the optical axis in said Faraday rotator, said central block being adjoined by at least two adjacent blocks of permanent magnet material with magnetization oriented substantially perpendicular to said central magnet block and the beam path plane, the poles of magnets in each said magnet set being the same where the magnets border the beam path plane, for producing an intense, unidirectional magnetic field in the space between the magnet sets with the unidirectional magnetic field having a predominant component thereof directed generally parallel to the direction of the beam path. |
