Asymmetric double-core fiber for hydraulic pressure sensing

• Published in: Optical fiber technology 2019-03, Vol.48, p.194-198
• Main Authors: Zhou, Yan, Deng, Yadong, She, Lijuan, Chen, Daru, Yu, Zhangwei, Qiang, Zexuan, Yang, Wenshao
• Format: Article
• Language: English
• Subjects: Double-core fiber; Fiber sensor; Finite element method; Hydraulic pressure
• ISSN: 1068-5200; 1095-9912
• DOI: 10.1016/j.yofte.2019.01.005

•An ADCF is designed with large pressure-induced difference of the refractive indices of the two fiber cores up to 10−5/MPa.•A hydraulic pressure sensing system is designed without using a costly optical spectrum analyzer.•The hydraulic pressure sensor has sensing range from 0 to 900 MPa, sensitivity of 0.3 mm/MPa, and resolution of 0.22 MPa. We propose a novel asymmetric double-core fiber (ADCF) which provides an ADCF-based hydraulic pressure sensing system without using optical spectrum measurement based on a costly optical spectrum analyzer. The ADCF is designed with asymmetric double fiber cores and two side air holes, which ensure the asymmetric pressure-induced phase change for the guiding light in the two fiber cores. Based on the finite element method, optical properties of the ADCF under hydraulic pressure are investigated considering the fiber parameters such as the refractive index, the distance of two holes or two fiber cores, the size of two fiber cores and the fiber length. A hydraulic pressure sensing system based on the ADCF and a low-cost linear array charge coupled device (CCD) is proposed, where the hydraulic pressure demodulation is achieved by measuring the movement of the spatial interference pattern of the light from the double fiber cores of the ADCF. Numerical simulation shows that the hydraulic pressure sensor based on a 10-cm ADCF and a 2.867-cm CCD has a sensing range from 0 to 900 MPa and a sensitivity of 0.3 mm/MPa. In this paper, a low-cost CCD is used instead of a costly spectrometer, which greatly reduces the cost of the sensing system. The proposal for the ADCF and the solution for hydraulic pressure sensing are of great significance to promote the wide application of the hydraulic pressure fiber sensor.