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In-line fiber optic interferometric sensors in single-mode fibers.

Zhu T, Wu D, Liu M, Duan DW - Sensors (Basel) (2012)

Bottom Line: Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers.It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost.Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Optoelectronic Technology & Systems (Ministry of Education), Chongqing University, Chongqing 400044, China. zhutao@cqu.edu.cn

ABSTRACT
In-line fiber optic interferometers have attracted intensive attention for their potential sensing applications in refractive index, temperature, pressure and strain measurement, etc. Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers. It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost. In this paper, we review two kinds of typical in-line fiber optic interferometers formed in single-mode fibers fabricated with different post-processing techniques. Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the in-line MZI based on three tapers.
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f7-sensors-12-10430: Schematic diagram of the in-line MZI based on three tapers.

Mentions: In order to improve the sensitivity to RI, Wu et al. introduced a MZI based on three cascaded SMF tapers [63]. As shown in Figure 7, the taper-1 and the taper-3 were used as the splitters and combiners to form a MZI, and the middle weak taper was used to increase the evanescent field of the cladding mode excited by taper-1 in the external medium. The increment is small, but sufficient for the enhancement of the RI sensitivity. Figure 8(a) shows the transmission spectrum of the three-tapers-based MZI with interaction length L of ∼60 mm. The detail parameters of the tapers are: the diameter and the length of both taper-1 and taper-3 were ∼20 μm and ∼6.1 mm; the diameter and the length of taper-2 (weak taper) were ∼39 μm and ∼40.8 mm, respectively. To characterize the effects of the middle weak taper on RI sensitivity, they have also fabricated other two three-tapers-based MZIs (called weak taper-1, weak taper-2), and a two-tapers-based MZI without the weak taper (called two tapers); the named weak taper-3 MZI is shown in Figure 8(a). They almost have the same parameters for the side tapers and separation lengths, however, the weak tapers in the middle are different. Weak taper-3 has the longest length and the thinnest diameter, while the weak taper-1 is converse. Experimental results show that the RI sensitivities of the four sensors were ∼80 nm/RIU (two tapers), ∼125 nm/RIU (weak taper-1), ∼172 nm/RIU (weak taper-2), and 286 nm/RIU (weak taper-3), respectively, as shown in Figure 8(b). The Equation (2) shows that the RI sensitivity of MZI could be strengthened by increasing the interferometer length L, however, it is not good for a compact sensor. Thus, the weak taper will play an important role in improving the RI sensitivity of the three-tapers-based MZI. The sensitivity ∼286 nm/RIU of the three-tapers-based MZI with 60 mm interaction length could be comparable with that of the LPFG pair sensor with 62 mm interaction length (259 nm/RIU) [59].


In-line fiber optic interferometric sensors in single-mode fibers.

Zhu T, Wu D, Liu M, Duan DW - Sensors (Basel) (2012)

Schematic diagram of the in-line MZI based on three tapers.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472836&req=5

f7-sensors-12-10430: Schematic diagram of the in-line MZI based on three tapers.
Mentions: In order to improve the sensitivity to RI, Wu et al. introduced a MZI based on three cascaded SMF tapers [63]. As shown in Figure 7, the taper-1 and the taper-3 were used as the splitters and combiners to form a MZI, and the middle weak taper was used to increase the evanescent field of the cladding mode excited by taper-1 in the external medium. The increment is small, but sufficient for the enhancement of the RI sensitivity. Figure 8(a) shows the transmission spectrum of the three-tapers-based MZI with interaction length L of ∼60 mm. The detail parameters of the tapers are: the diameter and the length of both taper-1 and taper-3 were ∼20 μm and ∼6.1 mm; the diameter and the length of taper-2 (weak taper) were ∼39 μm and ∼40.8 mm, respectively. To characterize the effects of the middle weak taper on RI sensitivity, they have also fabricated other two three-tapers-based MZIs (called weak taper-1, weak taper-2), and a two-tapers-based MZI without the weak taper (called two tapers); the named weak taper-3 MZI is shown in Figure 8(a). They almost have the same parameters for the side tapers and separation lengths, however, the weak tapers in the middle are different. Weak taper-3 has the longest length and the thinnest diameter, while the weak taper-1 is converse. Experimental results show that the RI sensitivities of the four sensors were ∼80 nm/RIU (two tapers), ∼125 nm/RIU (weak taper-1), ∼172 nm/RIU (weak taper-2), and 286 nm/RIU (weak taper-3), respectively, as shown in Figure 8(b). The Equation (2) shows that the RI sensitivity of MZI could be strengthened by increasing the interferometer length L, however, it is not good for a compact sensor. Thus, the weak taper will play an important role in improving the RI sensitivity of the three-tapers-based MZI. The sensitivity ∼286 nm/RIU of the three-tapers-based MZI with 60 mm interaction length could be comparable with that of the LPFG pair sensor with 62 mm interaction length (259 nm/RIU) [59].

Bottom Line: Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers.It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost.Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Optoelectronic Technology & Systems (Ministry of Education), Chongqing University, Chongqing 400044, China. zhutao@cqu.edu.cn

ABSTRACT
In-line fiber optic interferometers have attracted intensive attention for their potential sensing applications in refractive index, temperature, pressure and strain measurement, etc. Typical in-line fiber-optic interferometers are of two types: Fabry-Perot interferometers and core-cladding-mode interferometers. It's known that the in-line fiber optic interferometers based on single-mode fibers can exhibit compact structures, easy fabrication and low cost. In this paper, we review two kinds of typical in-line fiber optic interferometers formed in single-mode fibers fabricated with different post-processing techniques. Also, some recently reported specific technologies for fabricating such fiber optic interferometers are presented.

No MeSH data available.


Related in: MedlinePlus