Abstract

We propose and demonstrate a Fabry-Perot (F-P) optical fiber tip sensor for high-resolution refractive-index measurement fabricated by using 157-nm laser micromachining, for the first time to our knowledge. The sensor head consists of a short air F-P cavity near the tip of a single-mode fiber and the fiber tip. The external refractive index is determined according to the maximum fringe contrast of the interference fringes in the reflective spectrum of the sensor. Such a sensor can provide temperature-independent measurement of practically any refractive index larger than that of air and offers a refractive-index resolution of ~4×10-5 in its linear operating range. The experimental data agree well with the theoretical results.

© 2008 Optical Society of America

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References

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  1. B. Rothenhausler and W. Knoll, "Surface-plasmon microscopy," Nature 332, 615-617 (1988).
  2. D. Monzón-Hernández and J. Villatoro, "High-resolution refractive index sensing by means of a multiple-peak surface plasmon resonance optical fiber sensor," Sens. Actuators B 115, 227-231 (2006).
    [CrossRef]
  3. K. S. Chiang, Y. Liu, M. N. Ng, and X. Dong, "Analysis of etched long-period fiber grating and its response to external refractive index," Electron. Lett. 36, 966-967 (2000).
    [CrossRef]
  4. X. W. Shu, L. Zhang, and I. Bennion, "Sensitivity characteristics of long-period fiber gratings," J. Lightwave Technol. 20, 255-266 (2002).
    [CrossRef]
  5. J. F. Ding, A.P. Zhang, L. Y. Shao, J. H. Yan, and S. L. He, "Fiber-taper seeded long-period grating pair as a highly sensitive refractive-index sensor," IEEE Photon. Technol. Lett. 17, 1247 - 1249 (2005).
    [CrossRef]
  6. W. Liang, Y Y. Huang, Y. Xu, R. K. Lee, and A. Yariv, "Highly sensitive fiber Bragg grating refractive index sensors," Appl. Phys. Lett. 86, 151122 (2005).
    [CrossRef]
  7. J. Yang, L. Yang, Ch. Q. Xu, and Y. F. Li, "Optimization of cladding-structure-modified long-period-grating refractive-index sensors," J. Lightwave Technol. 25, 372-380 (2007).
    [CrossRef]
  8. M. C. Phan Huy, G. Laffont, Y. Frignac, V. Dewynter-Marty, P Ferdinand, P. Roy, J. M. Blondy, D. Pagnoux, W. Blanc and B. Dussardier, "Fibre Bragg grating photowriting in microstructured optical fibres for refractive index measurement," Meas. Sci. Technol. 17, 992-997 (2006).
    [CrossRef]
  9. G. Sun, A.G Kirk, "A highly sensitive index sensor based on attenuated total reflection inside a cavity," IEEE Lasers and Electro-Optics Society 356-357 (2006).
  10. J. L. Elster, M. E. Jones, M. K. Evans, S. M. Lenahan, C. A. Boyce, W. H. Velander, and R. Van Tassel, "Optical fiber extrinsic Fabry-Perot interferometric (EFPI)-based biosensors," Proc. SPIE 3911, 105-112 (2000).
    [CrossRef]
  11. X. W. Wang, J. Ch. Xu, Zh. Wang, K. L. Cooper, and A. B. Wang, "Intrinsic Fabry-Perot interferometer with a micrometric tip for biomedical applications," in Proceedings of the IEEE 32nd Annual Northeast on Bioengineering Conference 2006 p. 55-56 (2006).
    [CrossRef]

2007 (1)

2006 (2)

D. Monzón-Hernández and J. Villatoro, "High-resolution refractive index sensing by means of a multiple-peak surface plasmon resonance optical fiber sensor," Sens. Actuators B 115, 227-231 (2006).
[CrossRef]

M. C. Phan Huy, G. Laffont, Y. Frignac, V. Dewynter-Marty, P Ferdinand, P. Roy, J. M. Blondy, D. Pagnoux, W. Blanc and B. Dussardier, "Fibre Bragg grating photowriting in microstructured optical fibres for refractive index measurement," Meas. Sci. Technol. 17, 992-997 (2006).
[CrossRef]

2005 (2)

J. F. Ding, A.P. Zhang, L. Y. Shao, J. H. Yan, and S. L. He, "Fiber-taper seeded long-period grating pair as a highly sensitive refractive-index sensor," IEEE Photon. Technol. Lett. 17, 1247 - 1249 (2005).
[CrossRef]

W. Liang, Y Y. Huang, Y. Xu, R. K. Lee, and A. Yariv, "Highly sensitive fiber Bragg grating refractive index sensors," Appl. Phys. Lett. 86, 151122 (2005).
[CrossRef]

2002 (1)

2000 (2)

J. L. Elster, M. E. Jones, M. K. Evans, S. M. Lenahan, C. A. Boyce, W. H. Velander, and R. Van Tassel, "Optical fiber extrinsic Fabry-Perot interferometric (EFPI)-based biosensors," Proc. SPIE 3911, 105-112 (2000).
[CrossRef]

K. S. Chiang, Y. Liu, M. N. Ng, and X. Dong, "Analysis of etched long-period fiber grating and its response to external refractive index," Electron. Lett. 36, 966-967 (2000).
[CrossRef]

1988 (1)

B. Rothenhausler and W. Knoll, "Surface-plasmon microscopy," Nature 332, 615-617 (1988).

Appl. Phys. Lett. (1)

W. Liang, Y Y. Huang, Y. Xu, R. K. Lee, and A. Yariv, "Highly sensitive fiber Bragg grating refractive index sensors," Appl. Phys. Lett. 86, 151122 (2005).
[CrossRef]

Electron. Lett. (1)

K. S. Chiang, Y. Liu, M. N. Ng, and X. Dong, "Analysis of etched long-period fiber grating and its response to external refractive index," Electron. Lett. 36, 966-967 (2000).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

J. F. Ding, A.P. Zhang, L. Y. Shao, J. H. Yan, and S. L. He, "Fiber-taper seeded long-period grating pair as a highly sensitive refractive-index sensor," IEEE Photon. Technol. Lett. 17, 1247 - 1249 (2005).
[CrossRef]

J. Lightwave Technol. (2)

Meas. Sci. Technol. (1)

M. C. Phan Huy, G. Laffont, Y. Frignac, V. Dewynter-Marty, P Ferdinand, P. Roy, J. M. Blondy, D. Pagnoux, W. Blanc and B. Dussardier, "Fibre Bragg grating photowriting in microstructured optical fibres for refractive index measurement," Meas. Sci. Technol. 17, 992-997 (2006).
[CrossRef]

Nature (1)

B. Rothenhausler and W. Knoll, "Surface-plasmon microscopy," Nature 332, 615-617 (1988).

Proc. SPIE (1)

J. L. Elster, M. E. Jones, M. K. Evans, S. M. Lenahan, C. A. Boyce, W. H. Velander, and R. Van Tassel, "Optical fiber extrinsic Fabry-Perot interferometric (EFPI)-based biosensors," Proc. SPIE 3911, 105-112 (2000).
[CrossRef]

Sens. Actuators B (1)

D. Monzón-Hernández and J. Villatoro, "High-resolution refractive index sensing by means of a multiple-peak surface plasmon resonance optical fiber sensor," Sens. Actuators B 115, 227-231 (2006).
[CrossRef]

Other (2)

G. Sun, A.G Kirk, "A highly sensitive index sensor based on attenuated total reflection inside a cavity," IEEE Lasers and Electro-Optics Society 356-357 (2006).

X. W. Wang, J. Ch. Xu, Zh. Wang, K. L. Cooper, and A. B. Wang, "Intrinsic Fabry-Perot interferometer with a micrometric tip for biomedical applications," in Proceedings of the IEEE 32nd Annual Northeast on Bioengineering Conference 2006 p. 55-56 (2006).
[CrossRef]

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Figures (9)

Fig. 1.
Fig. 1.

(a). Structure of the sensor head, showing an in-fiber air cavity introduced near a cleaved fiber end, where the numbers “1”, “2”, and “3” label the three reflection surfaces in the structure. (b) The field amplitudes at the three reflection surfaces (the dashed arrows and the expressions within the boxes are for the case n′>n 0), where the symbols are defined in the text.

Fig. 2.
Fig. 2.

(a). Reflection spectra calculated for the cavity losses 0.02, 0.05, and 0.1, respectively, with A 1=A 2 fixed at 0.4. (b). Close-up of the fringes in (a). (c). Reflection spectra calculated for the transmission loss factors 0.4, 0.5 and 0.6, respectively, with α fixed at 0.02. (d). Close-up of the fringes in (c). The parameters of the sensor are given in Table 1 and n′=1.0 (air).

Fig. 3.
Fig. 3.

Variation of the maximum fringe contrast with the external refractive index (a) for the cavity losses α=0.02, 0.05, and 0.1, assuming A 1=A 2=0.4, and (b) for the transmission loss factors A 1=A 2=0.4, 0.5, and 0.6, assuming α=0.02. The parameters of the sensor are given in Table 1.

Fig. 4.
Fig. 4.

Spectra of the sensor for n′=1 (in air), n′=1.33, and n′=1.65, respectively.

Fig. 5.
Fig. 5.

(a) Microscopic image of the micromachined hole introduced on the fiber cross section. (b) Microscopic image of the fabricated sensor head. (c) Experimental setup for refractive-index sensing.

Fig. 6.
Fig. 6.

(a). Reflection spectrum of the sensor measured in air. (b) Close-up displays of the fringes for n′=1.0 (air), 1.33, and 1.404, respectively.

Fig. 7.
Fig. 7.

Variation of the fringe contrast with the refractive index for the range (a) from 1.0 to 1.62, and (b) from 1.33 to 1.62, showing close agreement between experimental and theoretical results.

Fig. 8.
Fig. 8.

(a). Power stability of the light source (b). Accuracy of the RI sensor

Fig. 9.
Fig. 9.

Variation of the fringe co ntrast measured in air with the temperature

Tables (2)

Tables Icon

Table 1. Values of the physical parameters of the sensor used in the calculation

Tables Icon

Table 2. Dependence of the RI sensitivity on the sensor parameters, where the numbers in the brackets are the RI resolutions obtained by assuming a fringe contrast resolution of 0.001dB

Equations (11)

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E r R 1 E i + ( 1 A 1 ) ( 1 α ) ( 1 R 1 ) R 2 E i e j 2 β L 1 + j π + ( 1 A 1 ) ( 1 A 2 ) ( 1 α ) ( 1 R 1 ) ( 1 R 2 ) R 3 E i e j β ( 2 L 1 + 2 L 2 ) for n n 0
E r R 1 E i + ( 1 A 1 ) ( 1 α ) ( 1 R 1 ) R 2 E i e j 2 β L 1 + j π + ( 1 A 1 ) ( 1 A 2 ) ( 1 α ) ( 1 R 1 ) ( 1 R 2 ) R 3 E i e [ j β ( 2 L 1 + 2 L 2 ) + j π ] for n > n 0
R FP ( λ ) = E r E i 2 = R 1 + ( 1 α ) 2 ( 1 A 1 ) 2 R 2 ( 1 R 1 ) 2 + ( 1 α ) 2 ( 1 A 1 ) 2 ( 1 A 2 ) 2 ( 1 R 1 ) 2 ( 1 R 2 ) 2 R 3 + 2 R 1 R 3 ( 1 α ) ( 1 A 1 ) ( 1 A 2 ) ( 1 R 1 ) ( 1 R 2 ) cos [ 4 π ( L 1 + n 0 L 2 ) λ ] 2 R 2 R 3 ( 1 α ) 2 ( 1 A 1 ) 2 ( 1 A 2 ) ( 1 R 1 ) 2 ( 1 R 2 ) cos [ 4 π ( 2 L 1 + n 0 L 2 ) λ ] 2 R 1 R 2 ( 1 α ) ( 1 A 1 ) ( 1 R 1 ) cos ( 4 π L 1 λ ) for n n 0
R FP ( λ ) = E r E i 2 = R 1 + ( 1 α ) 2 ( 1 A 1 ) 2 R 2 ( 1 R 1 ) 2 + ( 1 α ) 2 ( 1 A 1 ) 2 ( 1 A 2 ) 2 ( 1 R 1 ) 2 ( 1 R 2 ) 2 R 3 2 R 1 R 3 ( 1 α ) ( 1 A 1 ) ( 1 A 2 ) ( 1 R 1 ) ( 1 R 2 ) cos [ 4 π ( L 1 + n 0 L 2 ) λ ] + 2 R 2 R 3 ( 1 α ) 2 ( 1 A 1 ) 2 ( 1 A 2 ) ( 1 R 1 ) 2 ( 1 R 2 ) cos ( 4 π n 0 L 2 λ ) 2 R 1 R 2 ( 1 α ) ( 1 A 1 ) ( 1 R 1 ) cos ( 4 π L 1 λ ) for n > n 0
V ± 10 E n 0 F log e 10 ( n 0 n )
V = 10 Log 10 { A · ( n 0 n n 0 + n ) 2 + E ( λ 2 ) · ( n 0 n n 0 + n ) + F ( λ 2 ) A · ( n 0 n n 0 + n ) 2 + E ( λ 1 ) · ( n 0 n n 0 + n ) + F ( λ 1 ) }
V = 10 Log 10 { A · ( n 0 n n 0 + n ) 2 + E ( λ 1 ) · ( n 0 n n 0 + n ) + F ( λ 1 ) A · ( n 0 n n 0 + n ) 2 + E ( λ 2 ) · ( n 0 n n 0 + n ) + F ( λ 2 ) }
V 10 Log 10 { A · ( n 0 n n 0 + n ) 2 + E · ( n 0 n n 0 + n ) + F A · ( n 0 n n 0 + n ) 2 E · ( n 0 n n 0 + n ) + F }
V 10 Log 10 { E ( n 0 n n 0 + n ) + F E ( n 0 n n 0 + n ) + F }
V 10 Log 10 { E F · ( n 0 n n 0 + n ) + 1 E F · ( n 0 n n 0 + n ) + 1 }
V ± 10 E n 0 F log e 10 ( n 0 n )

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