| 摘要 |
PROBLEM TO BE SOLVED: To provide a light amplifier that can be freely changed in direction of amplification. SOLUTION: A light amplifying fiber 24,a wavelength multiplexer 26, and an optical circulator 28 are connected in series between signal light input/output terminals 20 and 22. Exciting light is inputted into the wavelength multiplexer 26 from an exciting light source 30. Exciting light emitted from the exciting light source 30 is directed to the light amplifying fiber 24 by the wavelength multiplexer 26. The optical circulator 28 is equipped with three ports A, B, and C and can be reversed in the direction of rotation by reversing an applied magnetic field. That is, either the one direction of rotation where the optical circular 28 outputs light inputted through the port A through the port B and outputs light inputted through the port B through the port C or the other direction of rotation where th optical circulator 28 outputs light inputted through the port B through the port A and outputs light inputted through the port A through the port C can be selected from outside. The port A of the optical circulator 28 is connected to the wavelength8 multiplexer 26, the port B is connected to the input/output terminal 22, and the port C is connected to a non-reflection terminal end 32. |
