To provide a variable optical attenuator capable of being miniaturized without necessitating a complex mechanism such as optical axis alignment and to provide a variable optical attenuation method.
An optical fiber 1 is inserted into a ferrule 2 and arranged in a casing 3. The ferrule 2 is fixed by an adhesive material 4 in the casing 3. The casing 3 is provided with a temperature adding means 5 which is connected with a temperature adjusting means 6 and adds temperature to the optical fiber 1 by heating/cooling the casing 3. The optical fiber 1, whose core is added with transition metal elements such as cobalt (Co), nickel (Ni), vanadium (V), is called an optical signal attenuation fiber. The optical signal attenuation amount of the optical fiber whose core is added with a transition metal is correlated with the temperature and is reproducible. Thus, once the correlation between the attenuation amount and the temperature is established, the attenuation amount of the optical signal can be adjusted by adding the prescribed temperature.
SHIRAISHI KEIKO
KIMOTO NAGAKAZU
TANIMOTO HAJIME
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