OPTICAL COUPLER

摘要

PURPOSE: To provide an optical coupler which does not depend on the polarized state of a message signal. CONSTITUTION: Filters 16 and 24 sensitive to a pair of polarization directions are used for multiplexing the message signal having a random polarization direction and a pair of pump signals having prescribed polarization directions on a common signal line are used. The filters 16 and 24 are arranged in optical elements (cubes, for example) 14 and 26 which are physically connected and which constitute an integrated optical device. Then, an optical isolator 13 is directly adhered to the output of the optical coupler which does not depend on the polarization direction. The positions of pump signal input to the filters 16 and 24 are changed and therefore the optical coupler can be applied to a same direction transmission system and a reverse direction transmission system.