| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical amplifying device and an optical transmission device which are restrained from varying in output light volume due to polarization dependence and capable of outputting light rays high in accuracy, stability, and output power by a method in which a polarization fixer is installed in a stage preceding an optical passive component or an optical branching filter, and a polarization maintainer is provided between the polarization fixer and the optical passive component or the optical branching filter. SOLUTION: Light rays outputted from an optical amplifier 1 are inputted into an optical branching device 2. The optical branching device 2 is composed of a polarization fixer 8, a polarization maintainer 9, and an optical branching filter 19, in which light passing through the polarization fixer 8 is fixed in polarization state, the outputted, and kept in polarization state by a polarization maintainer 9, and most of light rays outputted from the polarization maintainer 9 are transmitted as output signal light through an optical branching filter 10 as an optical coupler which branches off a part of signal light outputted from the polarization maintainer 9. As mentioned above, light rays are fixed in polarization state and branched off through the optical branching device 2. By this set up, an optical amplifier and an optical transmission device of this constitution are kept constant in insertion loss or branching ratio and capable of branching light rays independent of light polarization. |
