Patent ID: 6529317
Filing Date: 2003-03-04
Classification: H01S

Abstract:
An L-band EDFA comprising:an input terminal for receiving signal light; a pumping unit for producing a 1,530 nm wavelength band pumping light; a WDM coupler for multiplexing the signal light and the pumping light; and an EDF pumped by the pumping light for amplifying the signal light, wherein the pumping unit has a first amplifying stage and a second amplifying stage, said first stage comprising a tunable light source that has a capability to change the wavelength of the pumping light, 980 nm wavelength laser diode for producing 980 nm wavelength pumping light, a first WDM coupler for forwardly multiplexing the output light from the tunable light source and the output light from the 980 nm wavelength band laser diode, and a first EDF for amplifying the light provided from the first WDM coupler, said second amplifying stage comprising a first 1,480 nm wavelength band laser diode for producing 1,480 nm wavelength band pumping light, a second WDM coupler for multiplexing the output light from the first stage and the pumping light from the first 1,480 nm wavelength band laser diode, a second 1,480 nm wavelength band laser diode for producing 1,480 nm wavelength band pumping light, a third wavelength division multiplexing unit for backwardly multiplexing the output light from the second 1,480 nm wavelength band laser diode and the output light from the second WDM coupler, a second EDF for amplifying the light provided from the second WDM coupler, and an optical tunable filter for reducing the amplified spontaneous emission noise light from the amplified light of the second erbium doped fiber, and, said L-band EDFA further comprises isolators to remove a reflection noise, each of which is located between the first amplifying stage and the second amplifying stage, and between the second amplifying stage and an output terminal.