| 摘要 |
PROBLEM TO BE SOLVED: To provide an excitation device for Raman amplification which provides excitation beams for the Raman amplification with depolarization.SOLUTION: A Raman amplifier excitation device has: an excitation light source 11 which outputs a single polarization excitation beam; a first polarization holding coupler 13 which branches the excitation beam by two output ports to output the divided beams; a first branch polarization holding optical transmission medium 14 which propagates one of the excitation beams output from the first polarization holding coupler 13; a second branch polarization holding optical transmission medium 15 which propagates the other excitation beam; a second polarization holding coupler 16 to which the excitation beams output from the first and second branch polarization holding optical transmission media 14, 15 are input so that the polarization surfaces of the excitation beams become orthogonal to each other, and outputs the polarized and multiplexed excitation beam; and an excitation beam output port 17 which outputs the excitation beam from the second polarization holding coupler 16. A difference is provided in optical length of the first and second branch polarization holding optical transmission media 14, 15, and the difference in the optical length is taken longer than coherence length of the excitation beam. |
