Irradiated by infrared laser, the surface reducibility and adsorbability of Cu-Cr complex could be improved, owing to the interaction of photo-fragmentation and laser texturing. Analyzed by the binding energy spectra and the auger spectra, the valence states of chromium ion and copper ion were+3 and+1 after radiation respectively, which still had the reducibility to release electrons. In contrast with the near-infrared(NIR)1 064 nm and mid-infrared(MIR) 10 600 nm laser at the same average output power of 15 W, the reduced metal percentage in the Cu-Cr complex was obviously distinguished at the depth from nanometer to micron. After chemical plating, the average coating thickness and mean-square deviation of the NIR sample were 11.61 μm and 0.30 for copper layer, and 2.69 μm and 0.08 for nickel layer. The results were much better than those of the MIR sample.
A new wavelength division multiplexing method for fiber Bragg grating(FBG) sensors based on spectrum profile identification is proposed. In this method, FBGs and tilted FBG(TFBG) sensors are cascaded in a single fiber in one sensing channel. The different spectrum profiles enable the cross-correlation method to demodulate the wavelength. Therefore, the different types of sensors can occupy the same central wavelength band. Using this method, the multiplexing capacity is optimized. Experiment results demonstrate the feasibility of this method and it is useful for applications where large numbers of FBGs are needed.
针对光纤法布里-珀罗（F-P）压力传感器,建立了考虑热应力和残余气压的F-P腔长变化模型,进行了热应力和残余气压对传感器温度性能影响的理论分析。分析表明,热应力和残余气压的引入使F-P腔长改变量与温度的线性关系发生了变化,在外界施加100 k Pa压力,当腔内残余气压小于0.87 k Pa时,热应力起主要影响作用;当腔内残余气压大于0.87 k Pa时,残余气压起主要影响作用。制作了三种不同残余气压的光纤F-P压力传感器,在-20℃~70℃温度范围进行了实验研究,结果显示测量的腔长及其温度灵敏度随温度变化关系与理论分析基本一致。
