| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber amplifier capable of attaining optical amplification characteristics, as required, using low exciting power. SOLUTION: Fiber gratings 4a and 4b, having reflection characteristics of 1550 nm band respectively, are each arranged in front of a wavelength division multiplexing coupler 2a located in front of an erbium-doped fiber 1 and in the rear of a wavelength division multiplexing coupler 2b. The fiber gratings 4a and 4b enable spontaneously emitted light, which is not used for re-exciting erbium ions not to be emitted as an output light but is reflected towards the wavelength division multiplexing couplers 2a and 2b respectively and made incident on the erbium-doped fiber 1 again. |
