Patent ID: 6480328
Filing Date: 2002-11-12
Classification: H04B

Abstract:
An optical amplifier for amplifying wavelength division multiplexed signal light which contains respective optical signals of a first wavelength band and a second wavelength band, comprising:optical amplifying means for amplifying said wavelength division multiplexed signal light using a rare earth element doped fiber to which excitation light is supplied; a first optical circulator connected to one end of said rare earth element doped fiber; and a second optical circulator connected to the other end of said rare earth element doped fiber, wherein an optical signal of said first wavelength band is input to said rare earth element doped fiber via said first optical circulator and output from said rare earth element doped fiber via said second optical circulator, and an optical signal of said second wavelength band is input to said rare earth element doped fiber via said second optical circulator, and output from said rare earth element doped fiber via said first optical circulator, the signal light of said respective wavelength bands being propagated in mutually opposite directions inside the rare earth element doped fiber, and the wavelength division multiplexed signal light of said first wavelength band and the wavelength division multiplexed signal light of said second wavelength band are transmitted in the same direction.