Amplifying device, receiving device, and amplification method

A receiving device comprising:

• a light source configured to output excitation light;
• a depolarizer configured to change a degree of polarization of the excitation light in accordance with a setting;
• an amplifier configured to execute Raman amplification so as to amplify a polarized multiplexed optical signal by the excitation light of which the degree of the polarization has been changed by the depolarizer;
• a receiver configured to receive the polarized multiplexed optical signal subjected to the Raman amplification and amplified by the excitation light;
• a measurer configured to measure the power of a plurality of polarized light components multiplexed into the polarized multiplexed optical signal subjected to the Raman amplification and amplified by the excitation light;
• and
• an adjuster configured to calculate differences between the power of the plurality of polarized light components and adjust the setting of the depolarizer based on the differences between the power of the plurality of polarized light components.

An amplification method comprising:

• outputting excitation light from a light source;
• changing a degree of polarization of the excitation light by a depolarizer in accordance with a setting;
• executing Raman amplification so as to amplify a polarized multiplexed optical signal by the excitation light of which the degree of the polarization has been changed by the depolarizer;
• measuring the power of a plurality of polarized light components multiplexed into the polarized multiplexed optical signal subjected to the Raman amplification and amplified by the excitation light;
• calculating differences between the power of the plurality of polarized light components;
• and
• adjusting the setting of the depolarizer based on the differences between the power of the plurality of polarized light components.