| 摘要 |
PROBLEM TO BE SOLVED: To achieve a compact variable optical attenuator capable of changing transmission light power efficiently, in only light having a specific wavelength.SOLUTION: A variable optical attenuator 13 comprises: a transparent medium 130 for transmitting light; a first reflection membrane 131 disposed on a light incident face of the transparent medium 130; a second reflection membrane 132 disposed on a light emission face of the transparent medium 130; and a resonance length variable medium 135 for changing optical resonance length between the reflection membranes 131, 132. The first reflection membrane 131 has a first reflectance for transmitting partially at least light having a first wavelength λ1, out of lights having the first wavelength λ1 and having second wavelength λ2. The second reflection membrane 132 has a second reflectance lower than the first reflectance to the light having the first wavelength λ1, and has a third reflectance lower than the second reflectance to the light having the second wavelength λ2.SELECTED DRAWING: Figure 1 |
