External optical feedback effects due to reflection, Rayleigh backscattering and coherent Rayleigh backscattering in fiber distributed feedback (DFB) fiber laser sensor system have been investigated. If the feedback intensity exceeds critical amount, excess noise would be induced in the demodulator. The maximum tolerable intensity back-reflection coefficient Rc and backscattering coefficient Sc into a fiber DFB laser with lead fiber length from 1 m to 37.5 km before the onset of instabilities are shown. Rc is found to decrease with increasing lead fiber length while Sc was relatively invariable with varying fiber length. The coherent Rayleigh backscattering (CRBS) would induce neglectable noise with a lead fiber exceeding 13.5 km. To eliminate these noises, one or two isolators should be incorporated in the system.
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机译：Use of Universal Mini External Fixator in the Management of Postosteomyelitic Defects in Short Tubular Bones in the Paediatric Population 使用通用迷你外固定支架(Universal Mini External Fixator, UMEX)在儿科病人中治理因骨髓炎造成在短管状骨的缺陷
