탄소나노튜브가 포함된 폴리머를 코팅한 광섬유격자를 이용한 광센서 연구

Abstract

Light Sensor Based Fiber Bragg Grating Coated With Polymer Including Carbon Nanotubes Jeong Min Seo Adviser : Prof. Tae-Jung Ahn, Ph.D. Department of Photonic Engineering, Graduate School of Chosun University In this study, we propose a novel type of optical sensor that involves mixing carbon nanotubes with acrylate polymer and coating it on a Fiber Bragg Grating (FBG) to detect light. This method utilizes the property of carbon nanotubes to bend in the direction of light propagation when illuminated. The coated carbon nanotube polymer on the FBG affects the grating spacing of the FBG, resulting in a measurable shift in the central reflection wavelength. To verify the light detection capability of the fabricated FBG optical sensor coated with carbon nanotube polymer, experiments were conducted using LEDs in the visible light range. The sensor with a 900 µm thick carbon nanotube polymer coating on a 125 µm diameter FBG showed a central wavelength shift of approximately 0.32 nm, while the sensor with the same thickness of coating on an 80 µm diameter FBG showed a shift of about 0.58 nm. The light absorption of carbon nanotubes at specific wavelengths was measured and confirmed, and the light detection responsiveness at wavelengths of 365, 465, and 620 nm was observed. To enhance the sensitivity of the carbon nanotube polymer-coated FBG sensor, the content of carbon nanotubes in the polymer was varied to determine the optimal concentration. In the sensor system, to reduce the insertion loss when fusing optical fibers of different diameters, the discharge amount and time conditions of the fusion splicer were altered to find the optimal conditions and applied to the optical sensor. Theoretical strain values based on fiber diameter were calculated, and sensors with varying fiber diameters and coating thicknesses were fabricated and tested to compare the experimental results with theoretical values. Through this research, the functionality of the carbon nanotube polymer-coated FBG optical sensor in detecting light was confirmed, and studies were conducted on improving sensitivity based on the carbon nanotube content in the polymer and the diameter and thickness of the fiber coating.