Pump power control for optical fiber amplifier

A gain-controllable multiple-pump fiber amplifier comprising:

• an input for receiving optical signals;
• an output for providing amplified optical signals;
• a first gain stage coupled between the input and the output and including a first optical fiber and a first pump;
• a second gain stage coupled between the input and the output and including a second optical fiber and a second pump;
• and
• a pump controller coupled to said first and second gain stages for adjusting the power output from the first and the second pumps to maintain a substantially constant gain, wherein the controller limits the lower power output from each of the first and the second pumps to above a minimum value to minimize noise, wherein the controller further computes a total gain of the amplifier as a function of total power output and total power input.

A gain-controllable multiple-pump fiber amplifier comprising:

• an input for receiving optical signals;
• an output for providing amplified optical signals;
• a first gain stage coupled between the input and the output and including a first optical fiber and a first pump;
• a second gain stage coupled between the input and the output and including a second optical fiber and a second pump;
• and
• a pump controller coupled to said first and second gain stages for adjusting the power output from the first and the second pumps to maintain a substantially constant gain, wherein the controller limits the lower power output from each of the first and the second pumps to above a minimum value to minimize noise, wherein the optical signals comprise a plurality of signal channels that may change in number, said controller controlling the first and second pumps to maintain a substantially constant gain per channel.

A gain-controllable fiber amplifier comprising:

• an input for receiving optical signals;
• an output for providing amplified optical signals;
• a first gain stage coupled between the input and the output and including a first optical fiber and a first pump;
• and
• a pump controller for controlling the first pump and adjusting the power output from the first pump to maintain a substantially constant gain, wherein the controller decreases the power output from the first pump as a function of a minimum value to minimize noise, wherein the minimum value comprises a substantially minimum value output for the first pump to support backward amplified spontaneous emission.

A method of controlling gain in a multiple-pump fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• amplifying the optical signal in a second gain stage including a second optical fiber and a second pump;
• controlling the amount of power output by the first and second pumps to maintain a substantially constant gain by adjusting the power output of the first and second pumps;
• measuring and storing a minimum value for the first and second pumps to support backward amplified spontaneous emission;
• decreasing the power output from the first pump as a function of the minimum value of the first pump to minimize noise;
• decreasing the power output from the second pump as a function of the minimum value of the second pump to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a multiple-pump fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• amplifying the optical signal in a second gain stage including a second optical fiber and a second pump;
• controlling the amount of power output by the first and second pumps to maintain a substantially constant gain by adjusting the power output of the first and second pumps;
• computing a total gain of the amplifier as a function of total power output and total power input;
• decreasing the power output from the first pump as a function of a minimum value of the first pump to minimize noise;
• decreasing the power output from the second pump as a function of a minimum value of the second pump to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a multiple-pump fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• amplifying the optical signal in a second gain stage including a second optical fiber and a second pump;
• adjusting gain of the amplifier as a function of the number of selected signal channels on the received optical signal to maintain a substantially constant gain per channel;
• controlling the amount of power output by the first and second pumps to maintain a substantially constant gain by adjusting the power output of the first and second pumps;
• decreasing the power output from the first pump as a function of a minimum value of the first pump to minimize noise;
• decreasing the power output from the second pump as a function of a minimum value of the second pump to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• controlling the amount of power output by the first pump to maintain a substantially constant gain by adjusting the power output of the first pump;
• determining a minimum value for the first pump to support backward amplified spontaneous emission;
• decreasing the power output from the first pump as a function of the minimum value to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• controlling the amount of power output by the first pump to maintain a substantially constant gain by adjusting the power output of the first pump;
• computing a total gain of the amplifier as a function of total power output and total power input;
• decreasing the power output from the first pump as a function of a minimum value to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a fiber amplifier, said method comprising the steps of:

• receiving optical signals;
• amplifying the optical signals in a first gain stage including a first optical fiber and a first pump;
• adjusting gain of the amplifier as a function of the number of selected signal channels on the received optical signal to maintain a substantially constant gain per channel;
• controlling the amount of power output by the first pump to maintain a substantially constant gain by adjusting the power output of the first pump;
• decreasing the power output from the first pump as a function of a minimum value to minimize noise;
• and
• providing an amplified output signal.

A method of controlling gain in a fiber amplifier with a controller, said method comprising the steps of:

• receiving optical signals;
• measuring gain of a fiber amplifier;
• determining if the measured gain has changed;
• increasing power to a first pump if the gain has decreased;
• retrieving a minimum value from memory for the first pump;
• measuring a value of the first pump indicative of pump output;
• comparing the measured pump value with the retrieved minimum value;
• decreasing power to the first pump if the measured pump value is greater than the minimum value;
• and
• limiting the power to the first pump to a minimum power value if the measured pump value is less than the minimum value.