Optical Fiber Sensors: Working Principle, Applications, and Limitations

Abstract

An optical fiber is a flexible, transparent, and cylindrical waveguide made of plastic or silica, with diameters slightly thicker than that of a human hair (Figure 1a). [1] Optical fibers deliver/guide light for long distances with low losses. Single-index optical fibers consist of a transparent core covered with a transparent cladding material of a lower refractive index. The total internal reflection allows for guiding light in the fiber core; however, based on the waveguide analysis the energy of the transferred light is not fully trapped in the fiber core but a portion of the light travels in the cladding as evanescent waves. When the incident light hits the core-clad interface at angles larger than its critical angle, the light is completely reflected and guided in the fiber. In contrast, the incident light which meets the interface at smaller angles is refracted into the cladding to be lost. The critical angle is the minimum angle required to attain the total internal reflection, which is determined by the refractive index difference between the core and cladding materials. [2] Fibers can be classified into two categories based on the number of guided modes: single-mode and multimode fibers.

A Concise Review of the Progress in Photonic Sensing Devices

“…Optical fiber-based sensors have many advantages over traditional sensors, including their high sensitivity, fast response time, and immunity to EM interference. They are used in a wide range of applications, including structural monitoring, biomedical sensing, and environmental monitoring [88].…”

Fibre Bragg Grating Sensors for Condition Monitoring of High-Voltage Assets: A Review

“…Since first patented in 1967, several technologies and applications of fibre optic sensors have been developed [5]. However, most of the advancements on fibre optics were focused on telecommunication and the sensors market was dominated by electronic sensors [3,6]. Recent developments in the last 20 years show that fibre optic sensors have significant potential in all industries, including the power industry.…”

Agricultural soil health monitoring using photonic crystal fiber based on combined principles of surface plasmon resonance and interferometry for lead ion detection

“…10 Fiber optic sensors are based on evanescent field absorption, interferometry, surface plasmon resonance (SPR), fluorescence quenching, and light diffusion. 11 There are only few investigations where optical fiber sensor is used for agriculture health monitoring. For example, in one of our earlier works, we have proposed a microscopic sphere based optical fiber sensor for copper ion detection.…”

“…This is because of their properties, such as miniaturized structure, immune to EMI, biocompatibility, remote sensing, etc 10 . Fiber optic sensors are based on evanescent field absorption, interferometry, surface plasmon resonance (SPR), fluorescence quenching, and light diffusion 11 . There are only few investigations where optical fiber sensor is used for agriculture health monitoring.…”