US 7,068,422 B2Granted

Optical fiber amplification method and apparatus for controlling gain

AssigneeElectronics and Telecommunications Research Institute

InventorsJyung-chan Lee, Seung-il Myong, Moo-jung Chu, Hyun-jae Lee

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Abstract

Provided are an optical fiber amplification method and apparatus for controlling a gain. Initial values including target gains of first and second amplifications for an optical amplifier amplifying the input light signal are set. Power of the input light signal is measured and the power of first and second backward pump lights proceeding in the opposite direction to the input light signal is controlled based on the measured power. The input light signal is firstly amplified and a first amplification gain of the amplified light signal is calculated. Power of a first forward pump light proceeding in the same direction as the input light signal is controlled so that the first amplification gain can be substantially equal to the target gain of the first amplification. The firstly amplified light signal is secondly amplified and a second amplification gain with respect to the input light signal is calculated. The power of a second forward pump light proceeding in the same direction as the input light signal is controlled so that the second amplification gain can be substantially equal to the target gain of the second amplification.

Claims6

Dependent claims

An optical fiber amplification method by which a multi-wavelength multiplexed input signal is amplified using pump light, the optical fiber amplification method comprising:

(a) setting initial values including target gains of first and second amplifications for an optical amplifier amplifying the input light signal, the target gain for the first amplification is obtained by comparing power of a first input signal with measured power of a first output signal, the target gain for the second amplification is obtained by comparing power of the first input signal with measured power of a second output signal;
(b) indirectly measuring power of the input light signal and estimating number of channels of the input light signal based on power of the input light signal to control power of first and second backward pump lights proceeding in the opposite direction to the input light signal;
(c) firstly amplifying the input light signal and calculating a first amplification gain of the amplified light signal;
(d) controlling power of a first forward pump light proceeding in the same direction as the input light signal so that the first amplification gain can be substantially equal to the target gain of the first amplification;
(e) secondly amplifying the firstly amplified light signal and calculating a second amplification gain with respect to the input light signal;
and
(f) controlling the power of a second forward pump light proceeding in the same direction as the input light signal so that the second amplification gain can be substantially equal to the target gain of the second amplification.

4 more elements

An optical fiber amplifier amplifying a multi-wavelength multiplexed input signal, the optical fiber amplifier comprising:

a forward pump source portion which emits first pump lights and advances the first pump lights in the same direction as the input light signal;
a backward pump source portion which emits second pump lights and advances the second pump lights in the opposite direction to the input light signal;
a first amplifier which is configured to amplify the input light signal using a portion of the first pump lights and a portion of the second pump lights;
a second amplifier is configured to amplify a light signal output from the first amplifier using the rest of the first pump lights and the rest of the second pump lights;
and
a gain controller which is configured to indirectly measures power of the input light signal, controls power of the second pump lights based on the indirectly measured power, indirectly measures power of the light signal amplified by the first amplifier and power of the light signal amplified by the second amplifier, calculates first gain from the indirectly measured power of the first amplified light signal and the power of the input light signal by comparing power from the first amplified light signal with power of the input light signal, calculates second gain from the indirectly measured power of the second amplified light signal and the power of the input light signal by comparing power from the second amplified light signal with power of the input light signal and control the power of the first pump lights so that the first and second gains can be substantially equal to target gain values.

3 more elements

Dependencies are inferred from the claim text.