Optical element

Abstract

Provided is a Faraday rotator that is small, inexpensive, and capable of withstanding high-output and high-repetition laser radiation. An optical element (100) includes: a Faraday rotation element (110) that is reflective and rotates a polarization plane of reflected light with respect to a polarization plane of incident light; a magnet (130) provided on a side opposite to a surface of the Faraday rotation element through which surface the incident light enters the Faraday rotation element; and a coolant circulation section 140 and/or a cryostat (150) that cool(s) the Faraday rotation element.

Dependencies are inferred from the claim text.