| 摘要 |
PURPOSE:To measure an extinction ratio, by providing a disturbing part, which imparts the change of state to a part of an optical fiber for maintaining the plane of polarization, and injecting polarized light to a polarized axis accurately in a short time. CONSTITUTION:A polarizing plate 2a and a lambda/2 plate 3 are adjusted so that detected power becomes the minimum value, and the polarizing plate 2a and the lambda/2 plate 3 are fixed. A polarizing plate 2b is rotated, and the maximum value and the minimum value of the detected power are read by a detector 6. Based on the difference, an extinction ratio is obtained. An arbitrary vibration is imparted to an arbitrary part of an optical fiber 5 for maintaining the plane of polarization by a vibration applying part 7, e.g., a motor, a speaker and the like. When the polarized light, which agrees with an inherent polarized axis, is made incident to the optical fiber 5 for maintaining the plane of polarization, the device is not disturbed by the vibration and the polarizing direction of the transmitted light is not changed. Therefore, the optimum light injecting method is obtained. |
