| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of parts while maintaining excellent characteristics. SOLUTION: A 1st separating/synthesizing double refraction element 10, 1st and 2nd optical path controlling double refraction elements 11, 12 and a 2nd separating/synthesizing double refraction element 13 are arranged with intervals, a 1st polarization rotation means 14 for converting the polarization direction from an direction orthogonal to a parallel direction or from the direction parallel to the orthogonal direction is arranged between both elements 10, 11 and a 2nd polarization rotation means 17 is arranged between both elements 12, 13. The elements 11, 12 are oppositely arranged so that their optical axes are symmetrical about the center of their array and a 1/2 wavelength plate for rotating the polarization direction of light of a center optical path by 90 deg. is arranged between the elements 11, 12 to constitute an optical circulator. When±45 deg. variable Faraday rotators are used for the 1st and 2nd polarization rotation switching means in the same constitution, an optical switch can be constituted.
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