| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize the optical bias of 45 degrees simply and to obtain the high measuring accuracy in a broad temperature range. SOLUTION: In a reflecting part 20, a 1/4-wavelength plate 22 is provided on the optical path of the light emitted from the end of an optical fiber 3. A reflecting mirror 23 is arranged at a position, where the light transmitted through the 1/4-wavelength plate is reflected to the 1/4-wavelength plate. When the current is measured, setting is performed so that the axial direction of the crystal axis of the 1/4-wavelength plate 22 of the reflecting part 20 forms 22.5 degrees with the linearly polarized light applied from the incident/emitting end of the optical fiber 3. Thus, the light, which is transmitted through the 1/4-wavelength plate twice when the light is reflected at the reflecting part 20, becomes the linearly polarized light, whose plane of polarization is rotated by 45 degrees, and is propagated toward the incident/emitting end in the optical fiber. As a result, the optical bias of 45 degrees is applied on the light emitted from the incident/emitting end, and the Faraday rotating angle of the light is doubled.</p> |
