Refractive Index Measurement and Sensing Characteristics of Gold-Coated Three-Core Photonic Crystal Fiber

A symmetric three-core photonic crystal fiber optic sensor based on a gold film is presented, aiming to accurately measure the refractive index and evaluate its sensing characteristics. This sensor adopts the design of covering a gold film on a photonic crystal fiber, in which the fiber contains air holes of three different diameters. The performance of the sensor was analyzed by numerical simulation through the full vector finite element method. The results show that the sensor performance can be significantly affected by adjusting the diameter of the air holes and the thickness of the gold film. The sensor performs particularly well when the refractive index (RI) of the substance to be measured is in the range of 1.36 to 1.41, especially when the RI is 1.41. It has a maximum limiting loss value of 75 dB cm-1, a maximum amplitude sensitivity of 421 nm RIU-1, and a finest resolution of 6.67 × 10-6 RIU.These characteristics are essential for scientific research and industrial use where a high degree of accuracy is sought. This study not only provides a novel perspective on the design of three-core photonic crystal fibers, but also lays a solid foundation for the future development and optimization of fiber optic sensor technology. This innovation using gold films may inspire the development of more high-performance sensors and further expand the application areas of photonic crystal fiber technology. As the performance of sensors continues to improve, the prospects for commercialization of related technologies will become brighter. High-performance sensors are expected to be widely used in emerging industries such as smart manufacturing, automated monitoring systems and the Internet of Things, giving a strong boost to the development of these fields. The use of gold films demonstrates the possibility of applying new materials in fiber-optic sensors, and other types of metals or composites may be explored in the future to achieve even higher performance enhancements. With the advancement of sensor technology, they will be more widely used in a number of fields, contributing to the technological innovation and growth of related industries.