Optical amplifier with reduced non-linear signal impairments by optimum pumping configuration and method for using same

An optical waveguide amplifier having a forward pumping direction that extends from the input to the output and a rearward pumping direction that extends from the output to the input of said amplifier, said amplifier comprising:

• at least one gain producing optical waveguide having an input for receiving an optical source signal therein and an output,
• at least one excitation light source in optical communication with the optical waveguide, the excitation light source generating at least one excitation light;
• and
• wherein the source signal is amplified by pumping (i) a first excitation light from the excitation light source into the optical waveguide in the rearward pumping direction, and (ii) a second excitation light from the excitation light source into the optical waveguide in the forward direction;
• and
• wherein |ΔOSNR|<0.4 dB and FWMX □−25 dB, where OSNR stands for signal to noise ratio, and FWMX is four wave mixing cross talk.

An optical fiber communications system, comprising:

• a transmitter adapted to transmit a source signal;
• a receiver;
• at least one optical waveguide amplifier having an input in optical communication with the transmitter for receiving the source signal and an output in optical communication with the receiver for delivering the source signal to the receiver, the optical waveguide amplifier having a forward pumping direction that extends from the input to the output and a rearward pumping direction that extends from the output to the input;
• and
• at least one excitation light source in optical communication with the optical waveguide amplifier, the excitation light source generating at least one excitation light;
• and
• wherein the source signal is amplified by pumping a first excitation light from the excitation light source into the optical waveguide amplifier in the rearward pumping direction, and wherein the source signal is amplified by pumping a second excitation light from the excitation light source into the optical waveguide amplifier in the forward direction and wherein 1.5 < P r P f < 12
• and FWMX<−30 dB, where Pr is rearwardly propagating pump power and Pf is forward propagating pump power and FWMX is FWMX four wave mixing cross talk.

A method for amplifying an optical signal within an optical waveguide amplifier, comprising:

• providing at least one optical waveguide amplifier having an input end for receiving an optical source signal therein and an output end, wherein a forward pumping direction extends from the input end to the output end and a rearward pumping direction extends from the output end to the input end;
• providing at least one excitation light source in optical communication with the optical waveguide amplifier and capable of generating at least one excitation light;
• amplifying the source signal by pumping a first excitation light from the excitation light source in the rearward pumping direction;
• and
• amplifying the source signal by pumping a second excitation light from the excitation light source in the forward direction simultaneous with pumping the first excitation source, wherein 0 ≤ Δ ⁢ ⁢ O ⁢ ⁢ S ⁢ ⁢ N ⁢ ⁢ R ⁡ ( d ⁢ ⁢ B ) Δ ⁢ ⁢ P r ≤ 2 ⁢ dB .
• and FWMX <−25 dB, where OSNR is optical signal to noise ratio, ΔPr is pump power difference corresponding to pump power provided by said first excitation light, normalized to total pump power and, FWMX is cross talk due to four wave mixing cross talk.

A method for amplifying an optical signal within an optical waveguide amplifier, comprising:

• providing at least one optical waveguide amplifier having an input end for receiving an optical source signal therein and an output end, wherein a forward pumping direction extends from the input end to the output end and a rearward pumping direction extends from the output end to the input end;
• providing at least one excitation light source in optical communication with the optical waveguide amplifier and capable of generating at least one excitation light;
• amplifying the source signal by pumping a first excitation light from the excitation light source in the rearward pumping direction;
• and
• amplifying the source signal by pumping a second excitation light from the excitation light source in the forward direction simultaneous with pumping the first excitation light, wherein |OSNRmax−OSNRtot|<0.2 dB, FWMX□−40 dB, and 1.5 ⁢ □ P r P f ⁢ □ 12 ,
• where Pr is rearwardly propagating pump power and Pf is forward propagating pump power, and wherein ΔOSNR=OSNRmax−OSNR, where OSNRmax is the best achievable OSNR, OSNR stands for optical signal to noise ratio and, FWMX is four wave mixing cross talk.

An optical waveguide amplifier, comprising:

• at least one gain producing optical waveguide having an input for receiving an optical source signal therein and an output, the optical waveguide amplifier having a forward pumping direction that extends from the input to the output and a rearward pumping direction that extends from the output to the input;
• at least one excitation light source in optical communication with the optical waveguide, the excitation light source generating at least one excitation light;
• and
• wherein the source signal is amplified by pumping (i) a first excitation light from the excitation light source into the optical waveguide in the rearward pumping direction, and (ii) a second excitation light from the excitation light source into the optical waveguide amplifier in the forward direction;
• and
• wherein OSNR slope is less than 30°, where OSNR stands for optical signal to noise ratio, so that there is less than 0.4 dB change of OSNR per change in ΔPr of 0.1, where Pr is pump power provided by said first excitation source.