| 摘要 |
PURPOSE:To miniaturize structure, to increase coupling efficiency and to reduce cost by means of the small number of parts by setting up the optical axis of a polarizing prism for penetrating light radiated from a Faraday rotor to a direction different from a light transmitting direction. CONSTITUTION:Light from a light source 18 is rotationally polarized by 45 deg. through the Faraday rotor 20, made incident upon the polarizing prism 22, and since the optical axis 22a is set up to a direction different from incident light, separated into a normal light component 101 and an abnormal light component 102. When the component 101 is coupled with an SMF, its reflected feedback light is rotationally polarized by the rotor 20 and returned to a light source 18 as straight polarized light. The abnormal light component from the prism is rotationally polarized through the rotor 20 and projected to a direction different from the light source. Thereby, the structure can be miniaturized and the coupling efficiency can be increased by means of the small number of parts, and since only the small quantity of an expensive optical crystal material is used, cost can be reduced.
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