Optical amplifier and optical communication system including the same

An optical amplifier comprising:

• an optical waveguide disposed on a signal propagating line extending from a signal input end to a signal output end, said optical waveguide having a light-guiding region doped with Tm element;
• a pumping light supply system configured for supplying said optical waveguide with pumping light;
• said pumping light supply system including first light source means configured for supplying said optical waveguide with pumping light of one or more channels included in a wavelength band of 1.05 nm or 1.4 nm, and a structure configured for guiding a part of pumping light from said first light source means to said optical waveguide by way of an input end of said optical waveguide in a forward direction identical to an advancing direction of said signal light and guiding a part of pumping light from said first light source means to said optical waveguide by way of an output end of said optical waveguide in a backward direction opposite from said advancing direction of said signal light;
• a monitor system configured for monitoring light included in an amplification wavelength band at
• one or more positions on said signal propagating line, whereby powers of channels in the pumping light supplied to said optical waveguide are individually adjusted, according to a result of monitoring effected by said monitor system;
• and
• a controller configured to maintain a gain spectrum form in said optical waveguide and to maintain a power of signal light outputted from said optical waveguide at a constant design value, by adjusting only the magnitude of the amplification gain.

An optical amplifier comprising:

• an optical waveguide disposed on a signal propagating line extending from a signal input end to a signal output end, said optical waveguide having a light-guiding region doped with Tm element;
• a pumping light supply system for supplying said optical waveguide with pumping light component;
• a temperature detecting section for detecting a temperature of said optical waveguide or in the vicinity thereof, whereby powers of the pumping light components supplied into said optical waveguide are individually adjusted, according to a result of monitoring effected by said monitor system;
• and
• a controller configured to maintain a gain spectrum form in said optical waveguide and to maintain a power of signal light outputted from said optical waveguide at a constant design value, by adjusting only the magnitude of the amplification gain.