Compact enhanced performance optical isolator using a faraday rotator

Abstract

An optical isolator is disclosed that is particularly useful in the visible, infrared, and near-infrared portions of the electromagnetic spectrum. The rotator portion of the isolator produces a highly uniform magnetic intensity across its clear aperture. The optical isolator comprises a Faraday rotator that defines an optical axis, a respective polarizer on each end of the Faraday rotator and positioned on the optical axis, and a housing containing the Faraday rotator and the polarizers. The Faraday rotator comprises an optical rotator rod that defines the optical axis and a magnet assembly surrounding the optical rotator rod. The magnet assembly comprises eight trapezoidal cross section magnet sections arranged in a first group of four and a second group of four. The magnet sections in each group are placed adjacent one another along their respective nonparallel sides to form an overall square cross section for each group with a square cross section aperture through each group that surrounds the optical rotator rod. The first and second groups are arranged linearly adjacent to one another along the optical axis of the optical rod. The first group has its magnetic field perpendicular to and directed axially away from, the optical axis, and the second group has its magnetic field perpendicular to and directed axially towards, the optical axis of the optical rod.