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: In this paper, a review includes a brief theory about fiber optic sensors' operation and summarizes many research works carried out with them in which their operation and effectiveness are promoted to register some vital sign(s) as a possibility for their use in the medical, health care, and life support fields.
16 citations
TL;DR: A Fabry-Perot interferometer with inner air-cavity for ultra-sensitive strain measurement is presented in this paper, which is fabricated by fusion splicing of two sections of etched multimode fiber with offset.
Abstract: We demonstrate a Fabry-Perot interferometer with inner air-cavity for ultrasensitive strain measurement. The device is fabricated by fusion splicing of two sections of etched multimode fiber with offset. By selecting the appropriate value of the offset, the strain sensitivity can be greatly increased. In the case of introducing two-dimensional offset, the strain sensitivity can be increased by more than 4.5 pm/μe when compared with that without offset. The device is simple in fabrication, robust in structure, economic in cost, and convenient in operation, and has high potential in many strain sensing applications.
16 citations
Cites background from "Interferometric Fiber Optic Sensors..."
...The optical fiber FP interferometer sensors can be divided into two types: extrinsic and intrinsic [8]–[10]....
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TL;DR: In this article, a fiber Mach-Zehnder interferometer (MZI) based on no-core optical fiber (NCF) with large lateral offset structure was investigated theoretically and experimentally.
Abstract: In this work, a fiber Mach-Zehnder interferometer (MZI) based on no-core optical fiber (NCF) with large lateral offset structure was investigated theoretically and experimentally. For this interferometer, the light in the measurement path mainly propagates through the materials to be measured and the light in the reference path is well confined in the fiber. Therefore, the sensitivity for the refractive index measurement can be above 10,000 nm/refractive index unit (RIU), which is much higher than that of previously reported MZIs based on the interference principle of fiber modes. Owing to the high thermo-optical coefficient of polydimethylsiloxane (PDMS), the PDMS packaged sensor can measure temperature with a high sensitivity of 10.45 nm/oC. Moreover, the PDMS coating layer can also enhance the mechanical strength of the fiber structure for temperature measurement.
15 citations
15 citations
Cites methods from "Interferometric Fiber Optic Sensors..."
...The combined beam and the uncoupled beam in the core developed the interference.(25) The proposed MZI utilizes the SMS structure as shown in Figure 2....
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TL;DR: An all-fiber interferometric sensor for the simultaneous measurement of strain and temperature is presented, composed of a specially fabricated twin-core fiber spliced between two pieces of a single-mode fiber.
Abstract: In this paper we present an all-fiber interferometric sensor for the simultaneous measurement of strain and temperature. It is composed of a specially fabricated twin-core fiber spliced between two pieces of a single-mode fiber. Due to the refractive index difference between the two cores in a twin-core fiber, a differential interference pattern is produced at the sensor output. The phase response of the interferometer to strain and temperature is measured in the 850–1250 nm spectral range, showing zero sensitivity to strain at 1000 nm. Due to the significant difference in sensitivities to both parameters, our interferometer is suitable for two-parameter sensing. The simultaneous response of the interferometer to strain and temperature was studied using the two-wavelength interrogation method and a novel approach based on the spectral fitting of the differential phase response. As the latter technique uses all the gathered spectral information, it is more reliable and yields the results with better accuracy.
15 citations
Cites background from "Interferometric Fiber Optic Sensors..."
...Fiber-optic interferometers have been widely used for measurement applications [1] because of their small sizes, possibility of remote operation, high measurement precision, and sensitivity....
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References
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21 Dec 2017
TL;DR: In this paper, the authors present a comprehensive and engaging introduction to optics for intermediate and upper level undergraduate physics and engineering students, which allows instructors to select specialized content to suit individual curricular needs and goals.
Abstract: Introduction to Optics is now available in a re-issued edition from Cambridge University Press. Designed to offer a comprehensive and engaging introduction to intermediate and upper level undergraduate physics and engineering students, this text also allows instructors to select specialized content to suit individual curricular needs and goals. Specific features of the text, in terms of coverage beyond traditional areas, include extensive use of matrices in dealing with ray tracing, polarization, and multiple thin-film interference; three chapters devoted to lasers; a separate chapter on the optics of the eye; and individual chapters on holography, coherence, fiber optics, interferometry, Fourier optics, nonlinear optics, and Fresnel equations.
927 citations
TL;DR: A detailed mechanism of the surface plasmon resonance (SPR) technique for sensing purposes has been discussed in this paper, where different new techniques and models in this area that have been introduced are discussed in quite a detail.
Abstract: Since the introduction of optical fiber technology in the field of sensor based on the technique of surface plasmon resonance (SPR), fiber-optic SPR sensors have witnessed a lot of advancements. This paper reports on the past, present, and future scope of fiber-optic SPR sensors in the field of sensing of different chemical, physical, and biochemical parameters. A detailed mechanism of the SPR technique for sensing purposes has been discussed. Different new techniques and models in this area that have been introduced are discussed in quite a detail. We have tried to put the different advancements in the order of their chronological evolution. The content of the review article may be of great importance for the research community who are to take the field of fiber-optic SPR sensors as its research endeavors.
824 citations
TL;DR: In this paper, an approach to achieve simultaneous measurement of refractive index and temperature is proposed by using a Mach-Zehnder interferometer realized on tapered single-mode optical fiber.
Abstract: An approach to achieve simultaneous measurement of refractive index and temperature is proposed by using a Mach–Zehnder interferometer realized on tapered single-mode optical fiber. The attenuation peak wavelength of the interference with specific order in the transmission spectrum shifts with changes in the environmental refractive index and temperature. By utilizing S-band and C/L-band light sources, simultaneous discrimination of refractive index and temperature with the tapered fiber Mach–Zehnder interferometer is demonstrated with the corresponding sensitivities of −23.188 nm/RIU (refractive index unit) and 0.071 nm/ °C, and −26.087 nm/RIU (blueshift) and 0.077 nm/°C (redshift) for the interference orders of 169 and 144, respectively.
551 citations
"Interferometric Fiber Optic Sensors..." refers background in this paper
...By tapering a fiber at two points along the fiber, we can form an effective in-line MZI as shown in Figure 7(f) [55,56]....
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TL;DR: In this article, a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors was realized, which combines very small size, high finesse, small waist and mode volume, and good mode matching between the fiber and cavity modes.
Abstract: We have realized a fiber-based Fabry-Perot cavity with CO2 laser-machined mirrors. It combines very small size, high finesse F>=130000, small waist and mode volume, and good mode matching between the fiber and cavity modes. This combination of features is a major advance for cavity quantum electrodynamics (CQED), as shown in recent CQED experiments with Bose-Einstein condensates enabled by this cavity [Y. Colombe et al., Nature 450, 272 (2007)]. It should also be suitable for a wide range of other applications, including coupling to solid-state emitters, gas detection at the single-particle level, fiber-coupled single-photon sources and high-resolution optical filters with large stopband.
418 citations
"Interferometric Fiber Optic Sensors..." refers background in this paper
...Since it can utilize high reflecting mirrors, the extrinsic structure is useful to obtain a high finesse interference signal [23]....
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TL;DR: As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
Abstract: We propose simple and compact methods for implementing all-fiber interferometers. The interference between the core and the cladding modes of a photonic crystal fiber (PCF) is utilized. To excite the cladding modes from the fundamental core mode of a PCF, a coupling point or region is formed by using two methods. One is fusion splicing two pieces of a PCF with a small lateral offset, and the other is partially collapsing the air-holes in a single piece of PCF. By making another coupling point at a different location along the fiber, the proposed all-PCF interferometer is implemented. The spectral response of the interferometer is investigated mainly in terms of its wavelength spectrum. The spatial frequency of the spectrum was proportional to the physical length of the interferometer and the difference between the modal group indices of involved waveguide modes. For the splicing type interferometer, only a single spatial frequency component was dominantly observed, while the collapsing type was associated with several components at a time. By analyzing the spatial frequency spectrum of the wavelength spectrum, the modal group index differences of the PCF were obtained from 2.83×10-3 to 4.65 ×10-3 . As potential applications of the all-PCF interferometer, strain sensing is experimentally demonstrated and ultra-high temperature sensing is proposed.
418 citations
"Interferometric Fiber Optic Sensors..." refers background or methods in this paper
...However, in this case, coupling to several cladding modes was observed and controlling the number of involved modes was not so simple [51]....
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...Even with PCF, an MZI can be formed by simply fusion-splicing a piece of PCF between fibers with a small intentional deviation [51]....
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...In reference [51], as low as 2 dB splicing loss was achieved by making the mode coupling to dominantly one cladding mode of the PCF....
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