Interferometric Fiber Optic Sensors

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.

Transmission of a broadband light through a fiber optic loop: effect of nonlinear refractive index

“…These 2 waves passing along the fiber contour in 2 opposite directions obtain the same phase shifts (in the case of lack of Sagnac effect and/or nonlinear effects their optical paths are identical) [23,24] and once again interfere in the coupler. Thus, the amplitudes of waves leaving the fiber loop through the port via light that enters (reflected wave) and through another one (transmitted wave) are, accordingly:…”

Refractive index desensitized optical fiber temperature sensor

“…A number of sensing technologies including fiber Bragg gratings [4,5], long period gratings [6], and various configurations of interferometers [7,8], have been developed and studied for temperature measurement with reduced cost, increased sensitivity, or enhanced temperature range [6,8]. Recently, interference between guided modes of optics fibers for temperature fiber sensors have been reported [7,8,9,10].…”

“…Optical fiber interferometric (OFI) based temperature sensors offer advantages such as low-price and high temperature operation in comparison with structures using fiber gratings [6].…”

Investigation of a novel temperature-sensing mechanism based on strain-induced optical path-length difference in a multicore optical fiber

“…Interferometric fiber optic sensors have taken a particularly significant role in this area by introducing cost-effective optical devices with high sensitivity, small size, light weight, and sustainability against high temperatures [1][2][3][4][5][6].…”