Interferometric Fiber Optic Sensors
23 Feb 2012-Sensors (Multidisciplinary Digital Publishing Institute (MDPI))-Vol. 12, Iss: 3, pp 2467-2486
TL;DR: Each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields and some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications.
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.
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TL;DR: Recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.
Abstract: In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.
461 citations
Cites background or methods from "Interferometric Fiber Optic Sensors..."
...Sensors based on the Mach-Zender, and Michelson interferometers, also using long period gratings (LPGs) and photonic crystal fibres (PCFs) [14,15], have been used preferably for refractive index [16], temperature [17] or velocity measurement [18], while the Sagnac interferometer has been applied mainly to rotation measurements [19]....
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...The operation of interferometric sensors [14] is based on the change of the optical phase difference between two light waves with the same frequency, caused by the variation of a physical quantity....
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TL;DR: A wide variety of FPI sensors are reviewed in terms of fabrication methods, principle of operation and their sensing applications in a study on interferometric optical fiber sensors.
Abstract: Optical fibers have been involved in the area of sensing applications for more than four decades. Moreover, interferometric optical fiber sensors have attracted broad interest for their prospective applications in sensing temperature, refractive index, strain measurement, pressure, acoustic wave, vibration, magnetic field, and voltage. During this time, numerous types of interferometers have been developed such as Fabry-Perot, Michelson, Mach-Zehnder, Sagnac Fiber, and Common-path interferometers. Fabry-Perot interferometer (FPI) fiber-optic sensors have been extensively investigated for their exceedingly effective, simple fabrication as well as low cost aspects. In this study, a wide variety of FPI sensors are reviewed in terms of fabrication methods, principle of operation and their sensing applications. The chronology of the development of FPI sensors and their implementation in various applications are discussed.
291 citations
Cites background from "Interferometric Fiber Optic Sensors..."
...To the extent of the authors‘ knowledge, there are a few review articles that have partly talked about the common fabrication, sensing technologies and measurands of Fabry-Perot Interferometric fiber-optic sensors, including [44], which only covers microcavities that play a significant role in forming FPI, vibration sensing in [45], strain measurement in [46], acousto-ultrasonic sensing in [47], and also includes a number of recent reviews given in [48] where the recent trends of FPI fabrication, methods and application are presented....
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TL;DR: In this paper, the authors focus on optical refractive index (RI) sensors with no fluorescent labeling required, and utilize two parameters to characterize and compare the performance of optical RI sensors: sensitivity to RI change (denoted by symbol SRI) and figure of merit (in short, FoM).
Abstract: DOI: 10.1002/adom.201801433 Scientific American selects plasmonic sensing as the top 10 emerging technologies of 2018.[15] Almost every single new plasmonic or photonic structure would be explored to test its sensing ability.[16–29] These works tend to report the sensing performance of their own structure. Some declare that their sensitivity breaks the world record. However, there is still a missing literature on what the world record really is, the gap between the experiments and the theoretical limit, as well as the differences between metal-based plasmonic sensors and dielectric-based photonic sensors. To push plasmonic and photonic sensors into industrial applications, an optical sensing technology map is absolutely necessary. This review aims to cover a wide range of most representative plasmonic and photonic sensors, and place them into a single map. The sensor performances of different structures will be distinctly illustrated. Future researchers could plot the sensing ability of their new sensors into this technology map and gauge their performances in this field. In this review, we focus on optical refractive index (RI) sensors with no fluorescent labeling required. We will utilize two parameters to characterize and compare the performance of optical RI sensors: sensitivity to RI change (denoted by symbol SRI) and figure of merit (in short, FoM). For simplicity, we restrict our discussions to bulk RI change, where the change in RI occurs within the whole sample. There is another case where the RI variation occurs only within a very small volume close to the sensor surface. This surface RI sensitivity is proportional to the bulk RI sensitivity, the ratio of the thickness of the layer within which the surface RI variation occurs, and the penetration depth of the optical mode.[6] The bulk RI sensitivity defines the ratio of the change in sensor output (e.g., resonance angle, intensity, or resonant wavelength) to the bulk RI variations. Here, we limit our discussions to the spectral interrogations and the bulk RI sensitivity SRI is given by[3,5–7,30]
259 citations
TL;DR: An overview of the different types of FOS used for strain/temperature sensing in composite materials and their compatibility with and suitability for embedding inside a composite material is presented.
Abstract: This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements.
252 citations
Cites background from "Interferometric Fiber Optic Sensors..."
...A Fabry-Perot interferometer (FPI) generally comprises of two parallel reflecting surfaces separated by a certain distance [66]....
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...It is possible to tune the intensity of the interferometric modes of an EFPI sensor by varying the gap between the two reflecting surfaces [66]....
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...Interferometric fiber sensors [66] can also be employed for strain/temperature measurements in composite materials and this is discussed in detail in this section....
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...The reflection or transmission spectrum of an FPI is a wavelength dependent intensity modulation of the input light spectrum, resulting from the optical phase difference between the reflected and transmitted beams [66,67]....
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...The optical phase difference between reflected or transmitted beams at a particular wavelength of the FPI is basically specified as [66]:...
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TL;DR: In this article, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes, followed by discussion on the potentials of OFS in manufacturing.
Abstract: Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.
236 citations
References
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TL;DR: In this paper, a transmission-type EFPI (TEFPI) optical fiber sensor was presented, which has been improved by additional functions, and whose measuring system differs from that of the reflection-type optical fiber sensors using a singlemode fiber (SMF) and multimode (MMF) fibers as light guides and reflectors.
Abstract: The conventional reflection-type extrinsic Fabry-Perot interferometric (EFPI) optical fiber sensor has good sensitivity and resolution compared with other types of optical fiber sensors. However, they have the disadvantage that the distinction of strain direction of EFPI is difficult because of measurement method by only fringe counting. This paper presents the newly developed transmission-type EFPI (TEFPI) optical fiber sensor, which has been improved by additional functions, and whose measuring system differs from that of the reflection-type EFPI optical fiber sensors using a single-mode fiber (SMF) and multimode (MMF) fibers as light guides and reflectors, respectively. The output signal of the TEFPI optical fiber sensor was analyzed with the uniform plane wave-based model, the SMF power distribution-based model and the splice loss-based model; the analyzed signals were then verified experimentally. Based on the results of analysis, the TEFPI optical fiber sensor was fabricated using two single-mode fibers connected to the light source and optical receiver; this was then used in strain measurement. The strain measured by the TEFPI optical fiber sensor was compared with that measured by the electric strain gauge.
38 citations
"Interferometric Fiber Optic Sensors..." refers background in this paper
...FPI sensors can be largely classified into two categories: one is extrinsic and the other is intrinsic [21,22]....
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TL;DR: In this paper, a simple but sensitive hydrogen gas sensor composed of a palladium-coated long-period fiber grating (LPG) was demonstrated, where high-order cladding modes are excited.
Abstract: We demonstrate a simple but sensitive hydrogen gas sensor composed of a palladium-coated long-period fiber grating (LPG). By writing an LPG in a low core index fiber, high-order cladding modes are excited. As the palladium thin layer absorbs hydrogen, the effective refractive indexes of the cladding modes are affected, thus the resonant wavelengths of the LPG are changed with a high sensitivity. With 70-nm-thick coating, 7.5 nm of the hydrogen-induced spectral shift was achieved. The spectral response of the proposed sensor to hydrogen gas and its recovery with nitrogen gas are presented.
36 citations
TL;DR: In this article, an optical fiber twist sensor consisting of two mechanically induced long-period grating sections, whose birefringent axes are mutually orthogonal, was proposed and demonstrated.
Abstract: We propose and demonstrate, for the first time, an optical fiber twist sensor consisting of two mechanically induced long-period grating sections, whose birefringent axes are mutually orthogonal. The twist sensor, whose temperature stability is supposedly high and sensitivity is tunable by pressure, is based on the change in the loss peak separation due to the twist-induced polarization rotation.
35 citations
TL;DR: In this paper, a fiber-optic sensor for measuring the refractive index (RI) of a liquid sample is constructed from an extrinsic cavity formed by a micromirror and a lensed photonic crystal fiber (PCF) tip.
Abstract: We report a fiber-optic sensor for measuring the refractive index (RI) of a liquid sample. The sensing probe is constructed from an extrinsic cavity formed by a micromirror and a lensed photonic crystal fiber (PCF) tip. We show that PCF lens with an unconventionally large radius of curvature is bifunctional; an effective reflector as well as a collimator and thus suitable for realizing long single-arm interferometers, with a cavity length of the order of few mm. A sensing head suitable for measuring the refractive index (RI) of liquids is constructed by encapsulating the bifunctional lens tip and a micromirror in a glass tube. A hole is made in the glass-tube to allow free-flow of the liquid sample in-and-out of the cavity. The cavity length was about 1 mm. The group index of the liquid samples is obtained from the Fourier peak position of the interference signal measured in wavelength with optical spectrometer. The RIs of distilled water, acetone and ethanol (at 829 nm, 20°C) were measured to be 1.32822, 1.35416, and 1.35715, respectively. The resolution of the sensor was analytically found to be 2.6 × 10-5 and the response was experimentally shown to be linear.
32 citations
"Interferometric Fiber Optic Sensors..." refers background or methods in this paper
...(a) Schematic of an extrinsic FPI liquid RI sensor system based on a PCF lens, and (b) its reflection spectrum measured with an air cavity [35]....
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...Figure 2(a) illustrates the extrinsic sensor configuration based on a phonic crystal fiber (PCF) lens [35,36]....
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...The spectrum of a fabricated sensor, measured with an air cavity, is shown in Figure 2(b) [35]....
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...labeled RI was measured at a wavelength of 589 nm, different from our measurement done at 835 nm, there exists a constant offset between two RI data [35]....
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02 Jan 1998
TL;DR: In this article, a self-calibrated interferometric/intensity-based (SCIIB) fiber sensor is described, which operates on the absolute detection of signals form a Fabry-Perot inter-ferometric cavity.
Abstract: Self-calibrated interferometric/intensity-based (SCIIB) fiber sensors are describe in this paper. The sensor operates on the absolute detection of signals form a Fabry- Perot interferometric cavity. The incorporation of coherence-sliced self-calibration allows compensation for all unwanted factors, such as source power variations and fiber loss changes. Pressure sensors with various dynamic ranges were designed and fabricated based on the SCIIB scheme. Experimental results indicate that the novel sensor scheme offers excellent resolution and accuracy with absolute measurement and self-calibration function.
32 citations