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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

The RI sensitivity of the open cavity in-line MZI fabricated by different methods: (a) using femtosecond laser, as shown in Figure 9(d); (b) splicing with a large intentional lateral offset, as shown in Figure 9(e).
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f12-sensors-12-10430: The RI sensitivity of the open cavity in-line MZI fabricated by different methods: (a) using femtosecond laser, as shown in Figure 9(d); (b) splicing with a large intentional lateral offset, as shown in Figure 9(e).

Mentions: However, the above discussed in-line MZIs are based on multimode interference, the spectra are somewhat inhomogeneous since there are more than two modes involved in an inhomogeneous interference pattern. Exceptionally, the LPFG pair uses only one cladding mode in most cases. Although there is indeed one dominantly excited cladding mode to interfere with the core mode, the other weak cladding modes will still affect the sensing performance because different modes have different sensitivity to the external variations. The method to avoid the problem of multimode interference is to use the micro-cavity as one arm of the MZI, as shown in Figure 9(d,e) [72,82,83]. Figure 9(d) shows an open cavity in-line MZI based on a micro-cavity formed by using femtosecond laser to remove part of the fiber core and cladding. Meanwhile, Figure 9(e) shows another open cavity in-line MZI, in which a short section of SMF was spliced into two sections of SMFs with a large intentional lateral offset (∼62.5 μm). Such kinds of open cavity in-line MZIs have two different optical path: one is the air micro-cavity, and the other is the optical fiber (Figure 9(d) is the fiber core, Figure 9(e) is the fiber cladding, respectively). Due to the large index difference between the air cavity and the optical fiber (>0.1), a very short interferometer length can offer a large OPD, which allows a dramatic reduction of the size of MZI. Figure 12 shows that the open cavity in-line MZIs have a high liquid RI sensitivity of ∼9,370 nm/RIU in the range of 1.31∼1.335 [83], and even a high air RI sensitivity of ∼3,402 nm/RIU in the range of 1.0002–1.0022 [72].


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

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

The RI sensitivity of the open cavity in-line MZI fabricated by different methods: (a) using femtosecond laser, as shown in Figure 9(d); (b) splicing with a large intentional lateral offset, as shown in Figure 9(e).
© Copyright Policy
Related In: Results  -  Collection

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

f12-sensors-12-10430: The RI sensitivity of the open cavity in-line MZI fabricated by different methods: (a) using femtosecond laser, as shown in Figure 9(d); (b) splicing with a large intentional lateral offset, as shown in Figure 9(e).
Mentions: However, the above discussed in-line MZIs are based on multimode interference, the spectra are somewhat inhomogeneous since there are more than two modes involved in an inhomogeneous interference pattern. Exceptionally, the LPFG pair uses only one cladding mode in most cases. Although there is indeed one dominantly excited cladding mode to interfere with the core mode, the other weak cladding modes will still affect the sensing performance because different modes have different sensitivity to the external variations. The method to avoid the problem of multimode interference is to use the micro-cavity as one arm of the MZI, as shown in Figure 9(d,e) [72,82,83]. Figure 9(d) shows an open cavity in-line MZI based on a micro-cavity formed by using femtosecond laser to remove part of the fiber core and cladding. Meanwhile, Figure 9(e) shows another open cavity in-line MZI, in which a short section of SMF was spliced into two sections of SMFs with a large intentional lateral offset (∼62.5 μm). Such kinds of open cavity in-line MZIs have two different optical path: one is the air micro-cavity, and the other is the optical fiber (Figure 9(d) is the fiber core, Figure 9(e) is the fiber cladding, respectively). Due to the large index difference between the air cavity and the optical fiber (>0.1), a very short interferometer length can offer a large OPD, which allows a dramatic reduction of the size of MZI. Figure 12 shows that the open cavity in-line MZIs have a high liquid RI sensitivity of ∼9,370 nm/RIU in the range of 1.31∼1.335 [83], and even a high air RI sensitivity of ∼3,402 nm/RIU in the range of 1.0002–1.0022 [72].

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