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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 the PCF-based Michelson interferometer designed for temperature-insensitive liquid RI measurement, and (b) its spectral responses to RI and temperature [63]. A part of the core mode beam can be coupled to the cladding mode(s) by collapsing the PCF in a short length. Both beams reflected by the common mirror make interference. The silica rod fusion-spliced at the end of the PCF blocks the liquid.
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f10-sensors-12-02467: (a) Schematic of the PCF-based Michelson interferometer designed for temperature-insensitive liquid RI measurement, and (b) its spectral responses to RI and temperature [63]. A part of the core mode beam can be coupled to the cladding mode(s) by collapsing the PCF in a short length. Both beams reflected by the common mirror make interference. The silica rod fusion-spliced at the end of the PCF blocks the liquid.

Mentions: Typically, fiber optic sensors have cross sensitivity among measurands; especially they are easily affected by temperature variation. By using two types of fibers having different temperature sensitivities, the temperature dependency in RI measurement could be eliminated or reduced [66]. Another approach of reducing the temperature dependency was using PCF. As mentioned earlier, the PCF made of a fused silica is almost insensitive to temperature compared with conventional core-doped fibers. However, since the PCF has many air holes, in general, the MI type PCF sensor could not be immersed in the liquid specimen. Any liquid within the air holes of a PCF reduces the wave-guiding capability of the PCF. This problem was overcome simply by splicing a short piece of silica rod at the end of the PCF, which blocks liquid going inside the holes of the PCF as illustrated in Figure 10(a) [67]. Figure 10(b) shows the PCF-based MI sensor responding simultaneously to RI and surrounding temperature. There was no appreciable wavelength shift in the interference spectrum with the temperature variation; but it was heavily shifted with the RI variations. With the liquid having an RI near to the fiber material index, more precisely near to the modal index of the corresponding cladding mode, as much as 70 nm wavelength shift was observed.


Interferometric fiber optic sensors.

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

(a) Schematic of the PCF-based Michelson interferometer designed for temperature-insensitive liquid RI measurement, and (b) its spectral responses to RI and temperature [63]. A part of the core mode beam can be coupled to the cladding mode(s) by collapsing the PCF in a short length. Both beams reflected by the common mirror make interference. The silica rod fusion-spliced at the end of the PCF blocks the liquid.
© Copyright Policy
Related In: Results  -  Collection

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

f10-sensors-12-02467: (a) Schematic of the PCF-based Michelson interferometer designed for temperature-insensitive liquid RI measurement, and (b) its spectral responses to RI and temperature [63]. A part of the core mode beam can be coupled to the cladding mode(s) by collapsing the PCF in a short length. Both beams reflected by the common mirror make interference. The silica rod fusion-spliced at the end of the PCF blocks the liquid.
Mentions: Typically, fiber optic sensors have cross sensitivity among measurands; especially they are easily affected by temperature variation. By using two types of fibers having different temperature sensitivities, the temperature dependency in RI measurement could be eliminated or reduced [66]. Another approach of reducing the temperature dependency was using PCF. As mentioned earlier, the PCF made of a fused silica is almost insensitive to temperature compared with conventional core-doped fibers. However, since the PCF has many air holes, in general, the MI type PCF sensor could not be immersed in the liquid specimen. Any liquid within the air holes of a PCF reduces the wave-guiding capability of the PCF. This problem was overcome simply by splicing a short piece of silica rod at the end of the PCF, which blocks liquid going inside the holes of the PCF as illustrated in Figure 10(a) [67]. Figure 10(b) shows the PCF-based MI sensor responding simultaneously to RI and surrounding temperature. There was no appreciable wavelength shift in the interference spectrum with the temperature variation; but it was heavily shifted with the RI variations. With the liquid having an RI near to the fiber material index, more precisely near to the modal index of the corresponding cladding mode, as much as 70 nm wavelength shift was observed.

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