| 摘要 |
An object is to provide, at a lower cost, an isolator which is small in size, light in weight, and simple in manufacture. An optical isolator comprises a Faraday element 1 which is provided with polarization films formed on a light incident surface and a light emitting surface thereof and which is for rotating a polarization plane of incident light by an angle approximately equal to 45.degree., and a magnetic field applying mechanism 3 for applying a magnetic field to the Faraday element, wherein each of the polarization films 2 comprises a thin film made of a conductive material, the polarization films being formed on the light incident surface and the light emitting surface of the Faraday element 1, respectively, in the form of a unidirectional grating with an interval not greater than one tenth of the wavelength of light, one of the polarization films formed on the light emitting surface making, in a plane perpendicular to an optical axis, an angle with respect to the other polarization film 2a formed on the light incident surface, the angle being approximately equal to 45 in a direction similar to that of rotation of the polarization plane by the Faraday element 1.
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