Abstract

Short-period fiber Bragg gratings with weakly tilted grating planes generate multiple strong resonances in transmission. Our experimental results show that the wavelength separation between selected resonances allows the measurement of the refractive index of the medium surrounding the fiber for values between 1.25 and 1.44 with an accuracy approaching 1×104. The sensor element is 10  mm long and made from standard single-mode telecommunication grade optical fiber by ultraviolet light irradiation through a phase mask.

© 2007 Optical Society of America

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References

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  1. T. M. Niemczyk, "Refractive index measurement," in Physical Methods in Modern Chemical Analysis, T. Kuwana, ed. (Academic, 1980), Vol. 2, pp. 337-400.
  2. V. Bathia, "Applications of long-period gratings to single and multi-parameter sensing," Opt. Express 4, 457-466 (1999).
    [CrossRef]
  3. S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14, R49-R61 (2003).
    [CrossRef]
  4. N. D. Rees, S. W. James, R. P. Tatam, and G. J. Ashwell, "Optical fiber long-period gratings with Langmuir-Blodgett thin-film overlays," Opt. Lett. 27, 686-688 (2002).
    [CrossRef]
  5. A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
    [CrossRef]
  6. A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
    [CrossRef]
  7. H. J. Patrick, "Analysis of the response of long period fiber gratings to external index of refraction," J. Lightwave Technol. 16, 1606-1612 (1998).
    [CrossRef]
  8. T. Allsop, F. Floreani, K. P. Jedrzejewski, P. V. S. Marques, R. Romero, D. J. Webb, and I. Bennion, "Spectral characteristics of tapered LPG device as a sensing element for refractive index and temperature," J. Lightwave Technol. 24, 870-878 (2006).
    [CrossRef]
  9. G. Laffont and P. Ferdinand, "Tilted short-period fibre-Bragg-grating induced coupling to cladding modes for accurate refractometry," Meas. Sci. Technol. 12, 765-770 (2001).
    [CrossRef]
  10. C. Caucheteur and P. Megret, "Demodulation technique for weakly tilted fiber Bragg grating refractometer," IEEE Photon. Technol. Lett. 17, 2703-2705 (2005).
    [CrossRef]
  11. C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).
  12. T. Erdogan, "Cladding-mode resonances in short- and long period fiber grating filters," J. Opt. Soc. Am. A 14, 1760-1773 (1997).
    [CrossRef]
  13. Technical specifications for fused silica (Technical products division, Advanced Products Department, Corning Inc. MP-21-4, Corning, N.Y. 14831).
  14. C. Chen and J. Albert, "Strain-optic coefficients of the individual cladding modes of a single mode fiber: theory and experiment," Electron. Lett. 43, 21-22 (2006).
  15. K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
    [CrossRef]
  16. P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
    [CrossRef]
  17. Optigrating, from the Optiwave Corporation (Ottawa, Canada).
  18. High resolution swept laser interrogator, Model Si720, from Micron Optics, Inc., Atlanta, Ga.
  19. C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.
  20. A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
    [CrossRef] [PubMed]
  21. J. Yang, L. Yang, C. Xu, C. Xu, W. Huang, and Y. Li, "Long-period grating refractive index sensor with a modified cladding structure for large operational range and high sensitivity," Appl. Opt. 45, 6142-6147 (2006).
    [CrossRef] [PubMed]
  22. C. Zhao, X. Yang, M. S. Demokan, and W. Jin, "Simultaneous temperature and refractive index measurements using a 3° slanted multimode fiber Bragg grating," J. Lightwave Technol. 24, 879-883 (2006).
    [CrossRef]

2006 (4)

2005 (5)

A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
[CrossRef] [PubMed]

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

C. Caucheteur and P. Megret, "Demodulation technique for weakly tilted fiber Bragg grating refractometer," IEEE Photon. Technol. Lett. 17, 2703-2705 (2005).
[CrossRef]

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

2003 (1)

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14, R49-R61 (2003).
[CrossRef]

2002 (1)

2001 (1)

G. Laffont and P. Ferdinand, "Tilted short-period fibre-Bragg-grating induced coupling to cladding modes for accurate refractometry," Meas. Sci. Technol. 12, 765-770 (2001).
[CrossRef]

1999 (1)

1998 (1)

1997 (1)

1993 (2)

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

Albert, J.

C. Chen and J. Albert, "Strain-optic coefficients of the individual cladding modes of a single mode fiber: theory and experiment," Electron. Lett. 43, 21-22 (2006).

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.

Allsop, T.

Ashwell, G. J.

Atkins, R. M.

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

Bathia, V.

Bennion, I.

Bilodeau, F.

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

Campopiano, S.

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
[CrossRef] [PubMed]

Caucheteur, C.

C. Caucheteur and P. Megret, "Demodulation technique for weakly tilted fiber Bragg grating refractometer," IEEE Photon. Technol. Lett. 17, 2703-2705 (2005).
[CrossRef]

C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.

Chen, C.

C. Chen and J. Albert, "Strain-optic coefficients of the individual cladding modes of a single mode fiber: theory and experiment," Electron. Lett. 43, 21-22 (2006).

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.

Chryssis, A. N.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

Contessa, L.

Cusano, A.

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
[CrossRef] [PubMed]

Cutolo, A.

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
[CrossRef] [PubMed]

Dagenais, M.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

Demokan, M. S.

Erdogan, T.

Ferdinand, P.

G. Laffont and P. Ferdinand, "Tilted short-period fibre-Bragg-grating induced coupling to cladding modes for accurate refractometry," Meas. Sci. Technol. 12, 765-770 (2001).
[CrossRef]

Floreani, F.

Giordano, M.

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

Hill, K. O.

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

Huang, W.

Iadicicco, A.

A. Cusano, A. Iadicicco, P. Pilla, L. Contessa, S. Campopiano, and A. Cutolo, "Cladding mode reorganization in high-refractive index-coated long-period gratings: effects on the refractive-index sensitivity," Opt. Lett. 30, 2536-2538 (2005).
[CrossRef] [PubMed]

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

Jafari, A.

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

James, S. W.

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14, R49-R61 (2003).
[CrossRef]

N. D. Rees, S. W. James, R. P. Tatam, and G. J. Ashwell, "Optical fiber long-period gratings with Langmuir-Blodgett thin-film overlays," Opt. Lett. 27, 686-688 (2002).
[CrossRef]

Jedrzejewski, K. P.

Jin, W.

Johnson, D. C.

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

Laffont, G.

G. Laffont and P. Ferdinand, "Tilted short-period fibre-Bragg-grating induced coupling to cladding modes for accurate refractometry," Meas. Sci. Technol. 12, 765-770 (2001).
[CrossRef]

Lee, S. B.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

Lee, S. M.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

Lemaire, P. J.

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

Li, Y.

Malo, B.

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

Marques, P. V. S.

Megret, P.

C. Caucheteur and P. Megret, "Demodulation technique for weakly tilted fiber Bragg grating refractometer," IEEE Photon. Technol. Lett. 17, 2703-2705 (2005).
[CrossRef]

C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.

Mizrahi, V.

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

Niemczyk, T. M.

T. M. Niemczyk, "Refractive index measurement," in Physical Methods in Modern Chemical Analysis, T. Kuwana, ed. (Academic, 1980), Vol. 2, pp. 337-400.

Patrick, H. J.

Pilla, P.

Reed, W. A.

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

Rees, N. D.

Romero, R.

Saini, S. S.

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

Tatam, R. P.

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14, R49-R61 (2003).
[CrossRef]

N. D. Rees, S. W. James, R. P. Tatam, and G. J. Ashwell, "Optical fiber long-period gratings with Langmuir-Blodgett thin-film overlays," Opt. Lett. 27, 686-688 (2002).
[CrossRef]

Webb, D. J.

Xiong, L.

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

Xu, C.

Yang, J.

Yang, L.

Yang, X.

Zhao, C.

Appl. Opt. (1)

Appl. Phys. Lett. (1)

K. O. Hill, B. Malo, F. Bilodeau, D. C. Johnson, and J. Albert, "Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask," Appl. Phys. Lett. 62, 1035-1037 (1993).
[CrossRef]

Electron. Lett. (2)

P. J. Lemaire, R. M. Atkins, V. Mizrahi, and W. A. Reed, "High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres," Electron. Lett. 29, 1191-1193 (1993).
[CrossRef]

C. Chen and J. Albert, "Strain-optic coefficients of the individual cladding modes of a single mode fiber: theory and experiment," Electron. Lett. 43, 21-22 (2006).

IEEE Photon. Technol. Lett. (3)

C. Caucheteur and P. Megret, "Demodulation technique for weakly tilted fiber Bragg grating refractometer," IEEE Photon. Technol. Lett. 17, 2703-2705 (2005).
[CrossRef]

A. N. Chryssis, S. M. Lee, S. B. Lee, S. S. Saini, and M. Dagenais, "High sensitivity evanescent field fiber Bragg grating sensor," IEEE Photon. Technol. Lett. 17, 1253-1255 (2005).
[CrossRef]

A. Iadicicco, S. Campopiano, A. Cutolo, M. Giordano, and A. Cusano, "Nonuniform thinned fiber Bragg gratings for simultaneous refractive index and temperature measurements," IEEE Photon. Technol. Lett. 17, 1495-1497 (2005).
[CrossRef]

J. Lightwave Technol. (3)

J. Opt. Soc. Am. A (1)

Meas. Sci. Technol. (2)

G. Laffont and P. Ferdinand, "Tilted short-period fibre-Bragg-grating induced coupling to cladding modes for accurate refractometry," Meas. Sci. Technol. 12, 765-770 (2001).
[CrossRef]

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristics and application," Meas. Sci. Technol. 14, R49-R61 (2003).
[CrossRef]

Opt. Express (1)

Opt. Lett. (2)

Proc. SPIE (1)

C. Chen, L. Xiong, A. Jafari, and J. Albert, "Differential sensitivity characteristics of tilted fiber Bragg grating sensors," in Fiber Optic Sensor Technology and Applications IV, M. A. Marcus, B. Culshaw, and J. P. Dakin, eds., Proc. SPIE 6004, 600413 (2005).

Other (5)

T. M. Niemczyk, "Refractive index measurement," in Physical Methods in Modern Chemical Analysis, T. Kuwana, ed. (Academic, 1980), Vol. 2, pp. 337-400.

Technical specifications for fused silica (Technical products division, Advanced Products Department, Corning Inc. MP-21-4, Corning, N.Y. 14831).

Optigrating, from the Optiwave Corporation (Ottawa, Canada).

High resolution swept laser interrogator, Model Si720, from Micron Optics, Inc., Atlanta, Ga.

C. Chen, C. Caucheteur, P. Megret, and J. Albert, "Sensitivity of tilted fiber Bragg grating sensors with different cladding thicknesses," in 18th Conference on Optical Fiber Sensors (OFS-18), (2006), paper TuE31.

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Figures (7)

Fig. 1
Fig. 1

(Color online) Typical experimental TFBG transmission spectra (Corning SMF-28 fiber, θ = 6 ° ) . (a) Full spectrum measured in air. (b) Several measurements with various refractive indices of the outer medium near the Bragg resonance. (c) Same spectra as (b) but zooming in on a particular resonance near 1535.5   nm .

Fig. 2
Fig. 2

Experimental shift in the distance of a cladding-mode resonance from the Bragg wavelength as a function of the refractive index of a sugar solution at 589   nm .

Fig. 3
Fig. 3

Change in wavelength separation from the Bragg wavelength for four different cladding modes ( λ B 8 , 14 , 23 , and 28   nm : top to bottom) as a function of the refractive index of calibrated liquids. Solid symbols, experimental data at room temperature ( 23 ° C ) ; open symbols, experimental data at 50 ° C ; curves, simulations.

Fig. 4
Fig. 4

(Color online) (a) Experimental transmission spectrum of a TFBG with a tilt angle of 10° ( λ Bragg = 1566.810   nm ) . (b) Shift of a resonance near 1500   nm for various external media (solid curve, SRI = 1 .0 ; dotted curve, SRI = 1 .3058 ; dashed curve, SRI = 1 .3250 ; all the values are for λ = 1500   nm ).

Fig. 5
Fig. 5

Measured refractive index from the average of the predictions based on the shifts of four resonances ( 8 , 14 , 23 , and 28   nm ) versus actual refractive index.

Fig. 6
Fig. 6

(Color online) Reflection spectrum of packaged TFBG with a cleaved end downstream of the grating: bottom trace, as cleaved; top trace, with gold coating on the face of the cleave.

Fig. 7
Fig. 7

(Color online) Photograph of the packaged sensor (basically a connectorized piece of fiber 25   mm long with a TFBG in the length of the fiber outside the connector).

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

λ B = 2 n eff Λ ,
Λ = Λ g / cos   θ .
λ C ( i ) = ( n eff ( i ) + n C ( i ) ) Λ ,
Δ ( λ B λ C ( i ) ) / Δ n ext = Λ n C ( i ) / n ext .
Δ λ B / Δ T = 2 ( Λ n eff / T + n eff Λ / T ) ,
Δ λ C ( i ) / Δ T = Λ ( n eff ( i ) / T + n C ( i ) / T ) + ( n eff ( i ) + n C ( i ) ) Λ / T .
Λ ( 2 n eff / T n eff ( i ) / T n C ( i ) / T ) / ° C < Λ × 10 5 = 5 pm / ° C .
Λ 0.55 × 10 6 ( 2 n eff n eff ( i ) n C ( i ) ) / ° C < 0.12 pm / ° C,

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