| 摘要 |
PURPOSE:To easily switch a semiconductor laser light source which deteriorates to a stand-by light source by supplying light beams which are emitted by plural semiconductor lasers for excitation to an end part of an Er-doped optical fiber through a wavelength multiplexer or polarized wave multiplexer. CONSTITUTION:The output light of a 1st semiconductor laser 3 for excitation which emits light of about 1.45 - 1.46 mum and a 2nd semiconductor laser 4 for excitation which emits light of about 1.48 - 1.49 mum are made incident on a 1st wavelength multiplexer 5, whose excitation light output is multiplexed by a 2nd wavelength multiplexer 6 with signal light propagated in an input fiber 7 and made incident on the Er-doped optical fiber 8. This exciting light is propa gated in the optical fiber 8 in the same direction with the signal light to excite Er atoms to a high energy potential and signal light which is induced and emit ted is amplified. A dielectric multi-layered film 9 is arranged at the other end of the optical fiber 8 and the exciting light is reflected by the multi-layered film 9; and only the signal light is transmitted through the multi-layered film 9 and branched partially by an optical branching device 10, the majority enters an output fiber 11, and part of the light is made incident on a photodetector 12, which measures the quantity of the light. |
