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

A pump light generation device comprising:

• a first multi-mode laser configured to output first pump light;
• a second multi-mode laser configured to output second pump light;
• a first pump current/temperature controller configured to control a temperature and a pump current of the first multi-mode laser;
• a second pump current/temperature controller configured to control a temperature and a pump current of the second multi-mode laser;
• a first polarization maintaining optical amplifier configured to receive the first pump light as an input, amplifies a light intensity of the first pump light while keeping a polarization state of the first pump light in a linearly polarized wave, and outputs the first pump light;
• a second polarization maintaining optical amplifier configured to receive the second pump light as an input, amplifies a light intensity of the second pump light while keeping a polarization state of the second pump light in a linearly polarized wave, and outputs the second pump light;
• and
• a polarization multiplexing circuit configured to polarization-multiplex and outputs the first pump light with the light intensity amplified by the first polarization maintaining optical amplifier and the second pump light with the light intensity amplified by the second polarization maintaining optical amplifier,
• wherein the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that longitudinal modes included in the first pump light and longitudinal modes included in the second pump light do not overlap each other, and
• the first polarization maintaining optical amplifier and the second polarization maintaining optical amplifier perform control such that the intensities of the first pump light and the second pump light are equal to each other.

An optical amplification device comprising:

• a first multi-mode laser configured to output first pump light with longitudinal mode frequency intervals of δf1;
• a second multi-mode laser configured to output second pump light with longitudinal mode frequency intervals of δf2;
• a first pump current/temperature controller configured to control a temperature and a pump current of the first multi-mode laser;
• a second pump current/temperature controller configured to control a temperature and a pump current of the second multi-mode laser;
• 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 the second pump light output from the polarization multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal,
• wherein the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that longitudinal modes included in the first pump light and longitudinal modes included in the second pump light do not overlap each other, and
• in a case where the optical signal amplified by the first pump light and the second pump light is a digital signal of a baud rate fB, the frequency intervals δf1 and δf2 of the longitudinal modes are greater than the baud rate fB.