| 摘要 |
Light incident on an input optical fiber is separated into p-polarized light and s-polarized light by a birefringent crystal. A voltage to be applied to a liquid crystal element having electrodes associated with the ray axes of the polarized light waves is controlled in order to convert the p-polarized light into s-polarized so that both the polarized light waves will be s-polarized light. Otherwise, the s-polarized light is converted into p-polarized light so that both the polarized light waves will be p-polarized light. A polarized-wave separation film located behind the liquid crystal element transmits p-polarized light and reflects s-polarized light. When both the polarized light waves propagated through the liquid crystal element are s-polarized light, the light reflected from the polarized-wave separation film is reflected from a total-reflection film, and reflected again from the polarized-wave separation film. The resultant light falls on the birefringent crystal again via the liquid crystal element, and is restored to non-polarized light by the birefringent crystal. The non-polarized light then falls on a first output optical fiber. In contrast, when both the polarized light waves propagated through the liquid crystal element are p-polarized light, the p-polarized light is transmitted by the polarized-wave separation film, and then restored to non-polarized light after falling on the birefringent crystal via another liquid crystal element. The resultant light then falls on a second output optical fiber.
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