Abstract
Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.
Highlights
Over the last few decades optical fibers have been widely deployed in telecommunication industries owing to their special performance as the best light guidance [1]
A variety of studies have been made to utilize optical fibers as sensing indicators for temperature, strain, pressure, rotation, displacement, refractive index (RI), polarization, ultrasound, and so on [3,4,5,6,7,8,9,10]. Their sensing abilities have been considerably enhanced by utilizing innovative fiber optic technologies of fiber gratings, fiber interferometers, Brillouin/Raman scattering, surface Plasmon resonance (SPR), micro-structured fibers, nano-wires, specialty fiber couplers, etc. [11,12,13,14,15,16]
This paper aims to review and categorize fiber optic interferometric sensors according to their operating principles, fabrication methods, and application fields
Summary
Over the last few decades optical fibers have been widely deployed in telecommunication industries owing to their special performance as the best light guidance [1]. With the development of human-friendly smart materials, even health monitoring systems using fiber devices have attracted a great interest as future technologies. In spite of their increasing research outputs and extending application areas, mainly due to the relatively high cost of optical devices, only a few of them have been commercialized. Since the interferometers give a lot of temporal and spectral information as their signal, the measurand can be quantitatively determined by various means of detecting the changes in the wavelength, phase, intensity, frequency, bandwidth, and so on With these sensing indicators, they can give remarkable performance in large dynamic range, high accuracy, and high sensitivity [1]. The in-line structure offers several advantages such as easy alignment, high coupling efficiency, and high stability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
