US 5,710,660 A · Gain-controllable optical amplifier and optical gain-control method

Abstract

This invention provides an optical amplifier which has low noise characteristics for a wide range of input signal electric power. The optical amplifier has a plurality of cascaded optical amplifying units, a signal level detector, and a pump-source controller. The pump-source controller changes controlling objects from a pump-source corresponding to a first one of the optical amplifying units to a pump-source corresponding to a second one of the optical amplifying units according to a detection level of the signal level detector from a low level to a high level. When the detection level is outside of a control object range, the optical amplifier controls an output from the pump-source to stabilize. When the detection level is within the control object range, the optical amplifier controls an output from a pump-source of each of optical amplifying units according to the detection level.

Claims25

Dependent claims

A gain-controllable optical amplifier for amplifying an input signal, comprising:

a plurality of optical amplifying units cascaded each other, having an output side, wherein each of the plurality of optical amplifying units includes an optical fiber and a pump-source;
a signal level detector coupled to the output of the plurality of cascaded optical amplifying units, for detecting a power range of the input signal;
and
a pump-source controller, coupled to the pump-source in each of the optical amplifying units, having an output that controls a pump-source of a first optical amplifying unit of the plurality of optical amplifying units to generate a first output when the detected power range of the input signal is less than a first predetermined value, wherein the pump source controller controls a pump source of a second optical amplifying unit of the plurality of optical amplifying units to generate a second output when the detected power range of the input signal is less than a second predetermined value less than the first predetermined value.

1 more element

A method for controlling an optical amplifier including a plurality of cascaded optical amplifying units, each having a respective one of a plurality of pump-sources, the method comprising the steps of:

measuring a power range of an input signal that is provided to the plurality of cascaded optical amplifying units;
selecting one of the plurality of pump-sources depending on the power range of the input signal;
controlling a power of the selected pump-source to generate a first output when the power range of the input signal is less than a first predetermined value;
selecting a second of the plurality of pump sources depending on the power range of the input signal;
and
controlling a power of the second of the plurality of pump sources to generate a second output when the power range of the input signal is less than a second predetermined value less than the first predetermined value.

3 more elements

An apparatus for controlling an optical amplifier having a plurality of cascaded optical amplifying units, each having a respective one of a plurality of pump-sources, the apparatus comprising:

means for measuring a power range of an input signal that is provided to the plurality of cascaded optical amplifying units;
means for selecting one of the plurality of pump-sources based upon the power range of the input signal;
means for controlling a power of the selected pump-source to generate a first output when the power range of the input signal is less than a first predetermined value;
means for selecting a second of the plurality of pump sources depending on the power range of the input signal;
and
means for controlling a power of the second of the plurality of pump sources to generate a second output when the power range of the input signal is less than a second predetermined value less than the first predetermined value.

3 more elements

Dependencies are inferred from the claim text.

Gain-controllable optical amplifier and optical gain-control method

Life of this patent

Gain-controllable optical amplifier and optical gain-control method

Life of this patent

Abstract

Claims25