| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-resolution optical variable attenuator which has a large dynamic range and is suitable for a high-speed optical communication. SOLUTION: An optical attenuator member 21 for coarse adjustment and an optical attenuator member 31 for fine adjustment are movably disposed between an input side collimator 12 and an output side collimator 14 in the direction of an arrow. The optical variable attenuator member 21 for coarse adjustment is a stepped light variable attenuation plate provided with a plurality of decay areas 21a, 21b and 21c whose attenuation is different in a stepped shape, and is driven upward and downward by a step motor 51 and a rack-and- pinion 52. The optical attenuator member 31 for fine adjustment is an eccentric rotor made of a nonpearmeable material, and constitutes the rotor of an ultrasonic motor. Furthermore, a control means controls the step motor 51 and the ultrasonic motor so that the attenuation of an optical signal outputted from the output side collimator becomes a target value. |
