Patent ID: 7050231

Claim:
A Faraday rotator having a structure of a Fabry-Perot resonator, comprising: a laminate film; and a metal reflection film formed on a top or bottom surface of the laminate film, wherein the laminate film includes one magneto-optical thin film and two dielectric multilayer films, in each of which two kinds of dielectric thin films having refractive index different from each other are alternately laminated in such a manner as to make a periodic formation, and is configured such that the two dielectric multilayer films sandwich the magneto-optical thin film with their lamination patterns being symmetric with respect to the magneto-optical thin film, each of the dielectric thin films has an optical length of about λ/4, where λ is a wavelength of light, the metal reflection film is formed on a surface of one dielectric multilayer film of the two opposite to a surface fronting the magneto-optical thin film, the magneto-optical thin film is constructed in that an optical length of an irregular layer of the Fabry-Perot resonator is set to λ/2 or its integer multiples, and the dielectric multilayer films serve as a reflecting mirror of the Fabry-Perot resonator.