| 摘要 |
PURPOSE:To obtain a high extinction ratio by providing a branch interference type optical modulation part with a static phase control part which does not depend upon an applied electric field. CONSTITUTION:The branch interference type optical modulation part 3 is equipped with the static phase control part 4 which does not depend upon the applied electric field. Then mode light is selected by a combination of dynamic phase control by the branch interference type optical modulation part 3 by the applied electric field and static phase control by the static phase control part 4 which does not depend upon the electric field, or a combination of plural different static phase control means. Consequently, TM mode light is easily transmitted and TE mode light is easily cut off which is assumed to be difficult hitherto; and either the TE nor TM mode light can be selected according to an applied voltage, and the extremely high extinction ratio is obtained. |
