摘要 |
An optical amplifier including : an erbium-doped amplifier medium, a first excitation generator and a second excitation generator. The first excitation generator is adopted to cause a first type excitation of the at least one kind of rare-earth ions to cause a population inversion between the laser upper level and the laser lower level. The second excitation generator is adopted to cause a second type excitation of the at least one kind of rare-earth ions from the excited state absorption lower level to a high excited level which is equal to or higher than the laser upper level.
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