Patent ID: 6061171
Filing Date: 2000-05-09
Classification: H04B

Abstract:
An optical amplifier, comprising:an optical coupler having an input port, and first and second output ports, said input port being configured to be coupled to an optical communication path carrying a plurality of optical signals, each at a respective wavelength, said optical communication path having a first length;a first stage having a first segment of active optical fiber having a first end portion coupled to said first output port of said optical coupler, and a second end portion, said first segment of active optical fiber receiving said plurality of optical signals through said first end portion and outputting said plurality of optical signals through said second end portion;an optical attenuator having an input port coupled to said second end portion of said first segment of optical fiber, said optical attenuator having a control port that receives an attenuation control signal, and an output port, said input port of said optical attenuator receiving said plurality of optical signals, a first intermediate optical path coupling said input port of said optical attenuator to said second end portion of said first segment of optical fiber;a second stage having a second segment of active optical fiber having a first end portion coupled to said output port of said optical attenuator and a second end portion, said plurality of optical signals propagating through said optical attenuator and being supplied to said first end portion of said second segment of active optical fiber via said output port of said optical attenuator, said plurality of optical signals being output from said second segment of active optical fiber via said second end portion of said second segment of active optical fiber, a second intermediate optical path coupling said output port of said optical attenuator to said first end portion of said second segment of active optical fiber, lengths associated with said first and second intermediate optical paths being less than a length of said optical communication path;a photodetector coupled to said second output port of said coupler, said photodetector sensing a portion of said plurality of optical signals and generating an electrical signal in response thereto; andan attenuator adjustment circuit coupled to said photodetector and said control port of said optical attenuator, said attenuator adjustment circuit outputting said attenuation control signal in response to said electrical signal, said optical attenuator attenuating said plurality of optical signals in response to said attenuation control signal such that a power associated with each of said plurality of optical signals output from said second end portion of said second segment of active optical fiber is substantially the same.