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Interferometric fiber optic sensors.

Lee BH, Kim YH, Park KS, Eom JB, Kim MJ, Rho BS, Choi HY - Sensors (Basel) (2012)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Information and Communications, Gwangju Institute of Science and Technology, Buk-gu, Gwangju, Korea. leebh@gist.ac.kr

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.

No MeSH data available.


Related in: MedlinePlus

(a) The microscope image of an implemented double cavity FPI fiber sensor, and (b) its reflection spectrum [38]. The length of HOF is ∼70 μm, and the length of MMF is ∼360 μm. SMF; single mode fiber, HOF; hollow optical fiber, MMF; multi mode fiber.
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f4-sensors-12-02467: (a) The microscope image of an implemented double cavity FPI fiber sensor, and (b) its reflection spectrum [38]. The length of HOF is ∼70 μm, and the length of MMF is ∼360 μm. SMF; single mode fiber, HOF; hollow optical fiber, MMF; multi mode fiber.

Mentions: In addition to the extrinsic FPI sensors, a variety of intrinsic FPI sensors have been developed with various fiber structures. Among them, a double cavity structure fiber FPI is unique and interesting [37–39]. As shown in Figure 4(a), the double cavity can be simply formed by fusion-splicing a short piece of holey optical fiber (HOF) between a single mode fiber (SMF) and a piece of multimode fiber (MMF) [38]. The reflection spectrum of the double cavity FPI sensor, implemented with a piece of HOF of a length of ∼70 μm and a MMF of ∼360 μm, is shown in Figure 4(b). It has a rather complex fringe pattern due to the superposition of two cavities. The sinusoidal interference fringe is fast oscillating within a slowly varying envelop curve. However, the Fourier spectrum, Figure 5(a), shows that there are three dominant peaks except the DC peak resulting from the light source spectrum. The first peak near DC is caused by the short cavity 1 and the second peak is by the rather long cavity 2. The third peak is due to the combination of both cavities. When the distal end of the MMF was put into a liquid solution, the intensities of the second and the third peaks were decreased but the first peak was not changed as shown in Figure 5(a). It is understood that the Fresnel reflection only at the MMF end surface decreases with the RI of the liquid solution. The RI of the liquid solution calculated from the intensity variation of the Fourier peak is plotted in Figure 5(b) [38]. In this case, though the FPI uses air cavity, not a fiber cavity, since the HOF itself is a kind of fiber, it can be categorized as an intrinsic fiber sensor.


Interferometric fiber optic sensors.

Lee BH, Kim YH, Park KS, Eom JB, Kim MJ, Rho BS, Choi HY - Sensors (Basel) (2012)

(a) The microscope image of an implemented double cavity FPI fiber sensor, and (b) its reflection spectrum [38]. The length of HOF is ∼70 μm, and the length of MMF is ∼360 μm. SMF; single mode fiber, HOF; hollow optical fiber, MMF; multi mode fiber.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376629&req=5

f4-sensors-12-02467: (a) The microscope image of an implemented double cavity FPI fiber sensor, and (b) its reflection spectrum [38]. The length of HOF is ∼70 μm, and the length of MMF is ∼360 μm. SMF; single mode fiber, HOF; hollow optical fiber, MMF; multi mode fiber.
Mentions: In addition to the extrinsic FPI sensors, a variety of intrinsic FPI sensors have been developed with various fiber structures. Among them, a double cavity structure fiber FPI is unique and interesting [37–39]. As shown in Figure 4(a), the double cavity can be simply formed by fusion-splicing a short piece of holey optical fiber (HOF) between a single mode fiber (SMF) and a piece of multimode fiber (MMF) [38]. The reflection spectrum of the double cavity FPI sensor, implemented with a piece of HOF of a length of ∼70 μm and a MMF of ∼360 μm, is shown in Figure 4(b). It has a rather complex fringe pattern due to the superposition of two cavities. The sinusoidal interference fringe is fast oscillating within a slowly varying envelop curve. However, the Fourier spectrum, Figure 5(a), shows that there are three dominant peaks except the DC peak resulting from the light source spectrum. The first peak near DC is caused by the short cavity 1 and the second peak is by the rather long cavity 2. The third peak is due to the combination of both cavities. When the distal end of the MMF was put into a liquid solution, the intensities of the second and the third peaks were decreased but the first peak was not changed as shown in Figure 5(a). It is understood that the Fresnel reflection only at the MMF end surface decreases with the RI of the liquid solution. The RI of the liquid solution calculated from the intensity variation of the Fourier peak is plotted in Figure 5(b) [38]. In this case, though the FPI uses air cavity, not a fiber cavity, since the HOF itself is a kind of fiber, it can be categorized as an intrinsic fiber sensor.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Information and Communications, Gwangju Institute of Science and Technology, Buk-gu, Gwangju, Korea. leebh@gist.ac.kr

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.

No MeSH data available.


Related in: MedlinePlus