Optical fibre birefringence compensation mirror and current sensor

摘要

Disclosed is an optical fiber birefringence compensation mirror. Also disclosed is a current sensor wherein vibration resistance has been increased due to the optical connection of the optical fiber birefringence compensation mirror. The optical fiber birefringence compensation mirror includes: an optical fiber, a birefringence element, a lens, a magnet, a Faraday rotator, and a mirror. From the light incidence/emission end surface of the optical fiber, the birefringence element, Faraday rotator, and mirror are arranged in said order. Light comes in from the optical fiber, and is separated into two linearly polarised lights by the birefringence element. The polarisation planes of the two linearly polarised lights are rotated by the Faraday rotator, and the two linearly polarised lights are point-symmetrically reflected at one point by the mirror, then again rotated by the Faraday rotator, then re-combined into one light by the birefringence element and made to enter the optical fiber.

主权项

1. An optical fibre birefringence compensation mirror comprising:
an optical fibre; a birefringent element; a lens; a magnet; a Faraday rotator which is applied with a magnetic field from the magnet to be magnetically saturated and has a Faraday rotation angle of 45 degrees; and a mirror, wherein components of the birefringent element, the Faraday rotator, and the mirror are disposed in the order of the birefringent element, the Faraday rotator, and the mirror from a light incidence/emission end surface of the optical fibre, the optical fibre is of a single mode type, a light beam propagating through the optical fibre is divided into two perpendicular linearly polarized light beams of an ordinary ray and an extraordinary ray by the birefringent element to be condensed by the lens, the two linearly polarized light beams transmit through the Faraday rotator, therefore polarization planes thereof are rotated by 45 degrees, and the two linearly polarized light beams are reflected at one point on a surface of the mirror in points symmetry, the two reflected linearly polarized light beams re-transmit through the Faraday rotator, therefore the polarization planes of the two linearly polarized light beams are further rotated by 45 degrees, the two linearly polarized light beams are incident on the birefringent element again, consequently one light beam is re-combined, the re-combined light beam is incident on the optical fibre, and a shift amount of the extraordinary ray in the birefringent element is equal to or larger than twice a mode field diameter of the optical fibre.