OPTICAL FIBER ATTENUATOR WITH ATTENUATING DOPANT LIMITED TO A CENTRAL OR PERIPHERAL AREA OF FIBRE CORE

摘要

There is provided an optical attenuator which provides almost the same degree of attenuance even when the difference of wavelength of two different kinds of input optical signals is small. Further, an optical attenuator is realized with dopant concentration in the technically realizable range in increasing the difference of optical attenuance of two different kinds of input optical signals.