OPTICAL VARIABLE ATTENUATOR

摘要

An optical variable attenuator comprising a polarized wave rotating means including a plurality of polarizing means transmitting a specified polarized wave component of an input signal light, a Farady rotator array where a plurality of ferromagnetic Farady rotators are arrayed in series between the polarizing means, and field supply means provided to each Farady rotator in order to supply the Farady rotator with a magnetic field for rotating the polarized wave of the signal light, and a polarized wave rotational control means for determining the polarized wave rotational angle of the Faraday rotator array from a combination of polarized wave rotational angles determined for the respective Farady rotators by controlling the strength of magnetic field supplied to the Farady rotators.