| 摘要 |
An optical isolator having no dependence on direction of plane of polarization is provided by using a pair of polarization splitters, each comprising at least two parallel optical waveguides, and a birefringent crystal plate inserted in a groove formed obliquely in said waveguides. A plane formed by said two optical waveguides is parallel to vector normal to the incident surface of said birefringent crystal plate, the optical axis of said birefringent crystal plate is also parallel to said plane, and the following relationship is substantially satisfied: tan theta in=A/[ 2ROOT B(nin- 2ROOT B)] where A=(nO2-nE2) cos theta C sin theta C B=nE2 sin2 theta C+nO2 cos theta C nin: Refractive index of the optical waveguides nO: Refractive index of the birefringent crystal plate for ordinary light nE: Refractive index of the birefringent plate for extraordinary light theta in: Angle between axes of the optical waveguides and the vector normal to the incident surface of each of the birefringent crystal plates theta C: Angle between axes of the optical waveguides and the optical axis of the birefringent crystal plate (side opposite to theta in is deemed positive).
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