Pump light generation apparatus, optical amplifier and pump light generation method

An optical amplification device comprising:

• a first single-mode laser configured to output continuous wave light having a light frequency of fc1;
• a second single-mode laser configured to output continuous wave light having a light frequency of fc2 of a value different from fc1;
• a first wavelength number changer configured to change output light of the first single-mode laser and generates first pump light having a plurality of emission-line spectra whose light frequency is fc1+n×δf1 (n is an integer including a negative);
• and
• a second wavelength number changer configured to change output light of the second single-mode laser, generates second pump light having a plurality of emission-line spectra whose light frequency is fc2+n×δf2, and sets a frequency interval δf2 of a longitudinal mode to be as close as possible to a frequency interval δf1 of the longitudinal mode;
• a polarization-multiplexing circuit configured to polarization-multiplex and outputs the first pump light and the second pump light;
• and
• a gain medium, to which all of an optical signal and the first pump light and second pump light output from the polarization-multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal.

A pump light generation method comprising:

• by a first single-mode laser, outputting continuous wave light having a light frequency of fc1;
• by a second single-mode laser, outputting continuous wave light having a light frequency of fc2 of a value different from fc1;
• by a first wavelength number changer, changing output light of the first single-mode laser and generates first pump light having a plurality of emission-line spectra whose light frequency is fc1+n×δf1 (n is an integer including a negative);
• and
• by a second wavelength number changer, changing output light of the second single-mode laser, generates second pump light having a plurality of emission-line spectra whose light frequency is fc2+n×δf2, and sets a frequency interval δf2 of a longitudinal mode to be as close as possible to a frequency interval δf1 of the longitudinal mode;
• by a polarization-multiplexing circuit, polarization-multiplexing and outputs the first pump light and the second pump light;
• and
• a gain medium, to which all of an optical signal and the first pump light and second pump light output from the polarization-multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal.