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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) 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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f2-sensors-12-02467: (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].

Mentions: For measuring the RI of liquid, extrinsic FPI sensors are appropriate because the measurand can easily access the cavity. There has been an attempt to measure the liquid RI with the cavity-accessible intrinsic structure that is formed by a micro-hole, but it required elaborate laser machining process [24,25]. Figure 2(a) illustrates the extrinsic sensor configuration based on a phonic crystal fiber (PCF) lens [35,36]. The problem of low coupling efficiency of extrinsic FPI sensors could be overcome by introducing a PCF and a fiber lens on it. By using the electric arc discharge of a conventional fusion splicer, the air holes of the PCF could be collapsed and a lens was easily formed on its distal end. The PCF lens having a properly optimized curvature effectively acted as both a beam reflector and a collimator at the same time. The spectrum of a fabricated sensor, measured with an air cavity, is shown in Figure 2(b) [35]. We can see a high contrast sinusoidal interference fringe pattern especially in the magnified inset. As applying a series of liquid solutions having RIs from 1.400 to 1.438 with a step of 0.002 into the cavity, the reflection spectra were measured and their inverse fast Fourier transforms (IFFT) were taken in order to characterize them in the Fourier frequency domain.


Interferometric fiber optic sensors.

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

(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].
© Copyright Policy
Related In: Results  -  Collection

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

f2-sensors-12-02467: (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].
Mentions: For measuring the RI of liquid, extrinsic FPI sensors are appropriate because the measurand can easily access the cavity. There has been an attempt to measure the liquid RI with the cavity-accessible intrinsic structure that is formed by a micro-hole, but it required elaborate laser machining process [24,25]. Figure 2(a) illustrates the extrinsic sensor configuration based on a phonic crystal fiber (PCF) lens [35,36]. The problem of low coupling efficiency of extrinsic FPI sensors could be overcome by introducing a PCF and a fiber lens on it. By using the electric arc discharge of a conventional fusion splicer, the air holes of the PCF could be collapsed and a lens was easily formed on its distal end. The PCF lens having a properly optimized curvature effectively acted as both a beam reflector and a collimator at the same time. The spectrum of a fabricated sensor, measured with an air cavity, is shown in Figure 2(b) [35]. We can see a high contrast sinusoidal interference fringe pattern especially in the magnified inset. As applying a series of liquid solutions having RIs from 1.400 to 1.438 with a step of 0.002 into the cavity, the reflection spectra were measured and their inverse fast Fourier transforms (IFFT) were taken in order to characterize them in the Fourier frequency domain.

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