Research On Surface Metallization Of Optical Fiber Grating

The fiber optic sensor has been a hot research field in the past20years. It has a light weight, small size, resistance to corrosion and electromagnetic interference, etc. It facilitates the static and dynamic measurements. However, nowadays the package and actual engineering application of optical fiber grating sensors cannot be realized without the macromolecule glue, the aging ability of macromolecule glue restricts the wear capability of optical fiber grating sensor; and the glue will be softened or even broken up, when it was applied in higher than300degrees Centigrade, while lots of more harsh monitoring environments temperature have exceeded this range. In one word, the hermeticallity, cohere intensity, durability and heat resistance can’t meet the demands by using this package technology in the harsh environment. In order to improve the measurement accuracy of the optic fiber grating and make it call be applied to more high-temperature, need to protect the quartz optic fiber grating by metallized its surface, then fixed and packaged it by metallization technology.The optical fiber surface pretreatment craft processes and the technological conditions have been determined through the experiment, various craft procedures which influence the electroless plating nickel-phosphorus alloy coating quality have been analyzed, the most attentions have been put on the coarsening and the activation craft which determine the electroless coating quality. By optimizing the the activated liquid formulations and process conditions, In the fiber grating can be successfully electroless nickel plating without coarsening. According to generalized analysis, the optimal composition of chemical plating solution and the craft parameters are:Nickel sulfate20-30g/L; Inferior sodium phosphate25-30g/L; Complex agent22-30g/L; Sodium acetate10-15g/L; Potassium iodide5-20g/L; pH value4.4-5.0; temperature85-95℃; time20min.According to a series of tests and analysis of the coated ingredient and performance, a guidance and reproduction technical craft has been obtained. Scanning Electron Microscope (SEM) and Energy Dispersive Spectrum (EDS) have been used to observe the coating surface and analyze the composition. According to the results of SEM and optical microscope, the electroless plating coating, s morphology has been observed. The hot-vibrate experiment has been carried to characterized the performance of the coating.After electroless plating nickel-phosphor on the surface of optical liber, a series of research of electrical plating which increases the coating, s thickness have been studied.Various ingredients content in the electroless plating nickel, tin, zin, copper electrolyte and the technological conditions have been determined through the experiments. Finally, the coating with excellent welding performance and high brightness Increasing coating has been obtained. Appling this craft to optical fiber grating, then plating thickening fiber grating to do temperature sensor test.Electroplating and ordinary fiber grating all do the temperature sensor test. Comparing with ordinary fiber grating, the temperature sensing coefficient of plating thickening fiber grating has been increased considerably. Nickel plated grating sensitivity increased1.42times, tinned grating increased2.09times, galvanized grating increased2.42times, and the copper plating grating increased1.67times.