| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve such a problem that the polarized wave-dependent loss(PDL) is increased with the increase of attenuated amount in a conventional attenuator to be used for an optical transmission system. SOLUTION: In the optical attenuator to control the Faraday rotation angle of a beam transmitting a garnet single crystal is controlled by applying external magnetic fields of a fixed magnetic field and a variable magnetic field in two directions on the garnet single crystal having the Faraday effect, the Faraday element is constituted by using one or more garnet crystals having the Faraday effect and the member to fix the Faraday element and its periphery are provided with a positioning stopper for the top end of the yoke of a magnet to apply the variable magnetic field in the direction where the magnetic field is applied.</p> |
