| 摘要 |
PROBLEM TO BE SOLVED: To easily and accurately observe the power of an optical signal propagated in an optical fiber.SOLUTION: An optical device includes a variable optical attenuator 11, a spatial filter 13, and a light receiving element 15. In the variable optical attenuator 11, an optical signal from an input optical fiber 111 passes a variable optical attenuation element 115 and a collimator lens 117 to reach a branching mirror 19 and is branched into reflected light and transmitted light. The reflected light passes the collimator lens 117 to reach an output optical fiber 112. The transmitted light passes a collimator lens 131 and an optical fiber 135 constituting the spatial filter 13 and is propagated to the light receiving element 15. The collimator lens 131 and the optical fiber 135 are substantially equivalent to the collimator lens 117 and the output optical fiber which are disposed in a propagation path of the reflected light, and are disposed, in a propagation path of the transmitted light, in positions symmetrical to the collimator lens 117 and the output optical fiber 112 in the propagation path of the reflected light. |
