US 6,721,089 B1 · Method and apparatus for expanding the dynamic range of optical amplifiers

Abstract

The dynamic range of an optical amplifier is extended by the addition of a power control circuit. A switch is interposed between a current source and an optical pump supplying pumping light to the gain medium of the optical amplifier. A modulated signal such as a pulse-width modulated signal is used to actuate the switch and control a relative duration of the “on” and “off” periods of the electrical current supplied to the optical pump. Gain latency in the optical amplifier permits a substantially continuous signal to be output from the optical amplifier in response to the switched electrical current supply to the optical pump. A controller may used a feedback signal from the optical pump or from a power monitoring device to control the modulator and, thereby, the switch. A target pump power level, target gain or target amplified signal power level may also be applied in a feedback control loop that controls the modulator and switch. The invention also takes the form of a method that may be used to control a conventional optical amplifier in order to expand the dynamic range, particularly in the low power region.

Claims30

Dependent claims

An optical amplifier, comprising:

a gain media exhibiting gain latency and receiving an input optical signal;
an optical pump optically coupled to said gain media, said optical pump supplying pumping light to said gain media, said pumping light having at least one wavelength sufficient to induce gain in the input optical signal;
a current source operatively connected to said optical pump, said current source providing a drive current to said optical pump;
a switch interposed between said current source and said optical pump;
a modulator operatively connected to said switch;
said modulator generating modulated signals having a duty cycle and supplying the modulated signals to said switch, said switch actuating in response to the modulated signal such that said switch repeatedly turns the drive current “on” and “off”, and wherein the gain latency permits a substantially continuous signal to be output from the optical amplifier in response to said switch actuating.

3 more elements

Dependencies are inferred from the claim text.

Method and apparatus for expanding the dynamic range of optical amplifiers

Life of this patent

Method and apparatus for expanding the dynamic range of optical amplifiers

Life of this patent

Abstract

Claims30