Study Of The Optical Fiber Sensor Based On Polymer Coating

Optical fiber sensors have particular advantage in terrible working condition for their electromagnetic immunity, electrical insulation, high sensitivity, light weight, small in size, and so on. So many efforts were take on optical fiber sensors, recently. But optical fiber sensing based on fiber coating doesn’t attract any interests. This paper present several optical fiber sensor depend on polymer coating. Particularly, we invent a optical fiber sensor based on macro-bending optical fiber with polymer coating which present a high temperature sensitivity.The main work of this paper as follows:1. We research main type of optical fiber, the material of silica fiber coating and its characteristics. We also present specific application of silica fiber coating in sensing field which provide important enlightenment in our study. The simulation method of optical field distribution is also introduced. Which is a good mean for analyzing optical fiber sensors.2. The optical fiber sensor based on macro-bending optical fiber with polymer coating has been proposed. The sensor is only formed by tightly bended a normal SMF with coating in a shape of droplet and fixed by adhesive. The sensor can be used to measure temperature and refractive index by monitoring model interference between core model and high-order model in fiber coating. The proposed sensor with low-cost and simple structure present a high temperature sensitivity for large thermo-optic coefficient difference between silica and polymer.3. The displacement sensor based on a conical optical fiber probe made by etching a single mode fiber with polymer coating has been proposed. A visible light was put into the SMF, and the light was scattered at the conical probe. A CCD imaging sensor was used to collect the scattered light. And then, we can get the distance between the CCD and the fiber probe by calculating the area of flare spot. We also compare the experimental result with a flat fiber probe.