Long Period Fiber Grating for Refractive Index Sensing

Abstract

Refractive index (RI) sensors are very valuable in first level detection of changes to the environment. In this project an optical fiber-based sensor is proposed to detect changes in surrounding RI. Most optical fiber sensors require tapering to be done to enhance the light interaction with the surrounding. This causes the fiber to become fragile and difficult to handle. In this research, optical fibers with long period gratings (LPG) are proposed to overcome this issue. Zinc Oxide (ZnO) nanomaterial was deposited over the LPG region using seeding method to enhance the performance of the sensor. The LPG fiber sensor was then used to investigate RI changes in the environment. A broadband laser source was used as the input and an optical spectrum analyser was used to observe the output light spectrum of the LPG sensor for different refractive index mediums. The ZnO coated LPG showed a sensitivity of 428.57 nm/RIU over an RI range of 1 – 1.3578.