BI-DIRECTIONAL OPTICAL TRANSMITTING DEVICE CAPABLE OF CHANGING OVER BETWEEN ORDINARY AND SPARE

摘要

PURPOSE:To easily change over between an ordinary bi-directional optical transmitting line and a spare bi-directional optical transmitting line with a simple structure having a few number of parts. CONSTITUTION:The bi-directional optical transmitting device is composed of a magneto-optical switch 12, an ordinary bi-directional optical transmitting line 14 and a spare bi-directional optical transmitting line 16. The magneto- optical switch 12 is composed so that a half wavelength plate 24 and a Faraday rotator 26 are arranged between a first polarization beam splitter 20 and a second polarization beam splitter 22 and magnetic field is applied on the Faraday rotator 26 by means of an electromagnet. The ordinary bi-directional optical transmitting line 14 is coupled to a first transmitting port P3 juxtaposed on the side of the second polarization beam splitter 22 and the spare bi-directional optical transmitting line 16 is coupled to a second transmitting port P4.