All-POF coupling ratio-imbalanced Sagnac interferometer as a refractive index sensor

Temperature Sensors Based on Polymer Fiber Optic Interferometer

Temperature measurements are of great importance in many fields of human activities, including industry, technology, and science. For example, obtaining a certain temperature value or a sudden change in it can be the primary control marker of a chemical process. Fiber optic sensors have remarkable properties giving a broad range of applications. They enable continuous real-time temperature control in difficult-to-reach areas, in hazardous working environments (air pollution, chemical or ionizing contamination), and in the presence of electromagnetic disturbances. The use of fiber optic temperature sensors in polymer technology can significantly reduce the cost of their production. Moreover, the installation process and usage would be simplified. As a result, these types of sensors would become increasingly popular in industrial solutions. This review provides a critical overview of the latest development of fiber optic temperature sensors based on Fabry–Pérot interferometer made with polymer technology.

Alkali etched fiber Mach-Zehnder interferometer with compact sensor head

We demonstrate a scheme for fabricating compact fiber Mach-Zehnder interferometer (MZI). A section of Ge-doped fiber (GDF) is sandwiched between two single-mode fibers. The sandwich structure is side polished to make the core of GDF exposed to the surroundings. Alkali solution is utilized to etch the core of GDF. A compact fiber MZI is achieved when about half of the core is etched. Compared with the traditional ones, our scheme for fabricating fiber MZI has the characteristics of low cost, environmentally friendly, and regular transmission spectrum. This fiber MZI not only reduces the consumption of the sample, but also brings forth a good potential for micro-scale detection of refractive index.