Refractive Index Measurement of Liquids Based on Microstructured Optical Fibers

Abstract

This review is focused on microstructured optical fiber sensors developed in recent years for liquid RI sensing. The review is divided into three parts: the first section introduces a general view of the most relevant refractometric sensors that have been reported over the last thirty years. Section 2 discusses several microstructured optical fiber designs, namely, suspended-core fiber, photonic crystal fiber, large-core air-clad photonic crystal fiber, and others. This part is also divided into two main groups: the interferometric-based and resonance-based configurations. The sensing methods rely either on full/selective filling of the microstructured fiber air holes with a liquid analyte or by simply immersing the sensing fiber into the liquid analyte. The sensitivities and resolutions are tabled at the end of this section followed by a brief discussion of the obtained results. The last section concludes with some remarks about the microstructured fiber-based configurations developed for RI sensing and their potential for future applications.

A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

“…SPR sensors exhibit high sensitivity characteristics, which enables a new window for numerous promising applications including biological sample detection, antibody-antigen interaction, medical diagnosis, organic-chemical sensing, food quality control, bioimaging, environment monitoring, and so on [1][2][3][4]. The idea of a surface plasmon (SP) phenomenon was first theoretically demonstrated by Ritchie et al in the 1950s [5].…”

Temperature Sensor Based on an Asymmetric Two-Hole Fiber Using a Sagnac Interferometer

“…FOS advantages over electronic devices are well known such as lightweight, small size, high sensitivity and operation speed, immunity to electromagnetic interference, resistance to chemical corrosion, remote sensing, and the option of multiplexing optical signals. These suitable features have allowed a variety of studies to apply FOS as sensing indicators for temperature, rotation, strain, pressure, level, refractive index (RI), liquid contamination, and so on [1][2][3]. The current status, opportunities, and global perspective of FOS are described in [4][5][6][7].…”

Some refractometric features of dual-core chirped microstructured optical fibers

“…In recent years, microstructured optical fibers (MOFs), with unique light guiding properties, have been successfully applied to RI sensing. 1 The presence of air holes running along its entire length allows unprecedented sensitivity since the analyte being sensed can be inserted into the fiber holes and experience long range interaction with guided light while maintaining the waveguide external diameter, thereby ensuring a robust device.…”