Abstract

What is believed to be a novel long-period grating (LPG) refractive index sensor with a modified cladding structure is proposed and studied. In the proposed structure, the cladding of the fiber has a two-layer structure, i.e., a cladding layer of low refractive index with a reduced radius and an overlay of high refractive index. The sensitivity of the structure-modified LPG sensor to the ambient refractive index change as a function of the cladding layer and overlay parameters is investigated by way of modeling. It is found that an increase of the ambient refractive index causes a field redistribution of the cladding mode into the overlay when the parameters of the overlay are properly selected. It is shown that by reducing the radius of the cladding layer, the operational range of the LPG refractive index sensor can be as large as 0.195 (from 1.244 to 1.440) with a minimum sensitivity of 660  nm∕refractive index, which represents a 31% increase of operational range in comparison with the operational range obtained from the reported structure. The design guidelines for achieving this large operation range and high sensitivity are explained by investigating the dependence of the cladding modes on the radius of the cladding layer.

© 2006 Optical Society of America

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References

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  1. S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristic and application," Meas. Sci. Technol. 14, R49-R61 (2003).
    [CrossRef]
  2. H. J. Patrick, A. D. Kersey, and F. Bucholtz, "Analysis of the response of long period grating to external index of refraction," J. Lightwave Technol. 16, 1606-1612 (1998).
    [CrossRef]
  3. K. W. Chung and S. Yin, "Analysis of a widely tunable long-period grating by use of an ultrathin cladding layer and high-order cladding mode coupling," Opt. Lett. 29, 812-814 (2004).
    [CrossRef] [PubMed]
  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. I. Del Villar, I. R. Matias, and F. J. Arregui, "Optimization of sensitivity in long period fiber Gratings with overlay deposition," Opt. Express 13, 56-69 (2005).
    [CrossRef] [PubMed]
  6. Z. Wang, J. R. Heflin, R. H. Stolen, and S. Ramachandran, "Analysis of optical response of long period fiber gratings to nm-thick thin-film coating," Opt. Express 13, 2808-2813 (2005).
    [CrossRef] [PubMed]
  7. 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]
  8. T. Erdogan, "Fiber grating spectra," J. Lightwave Technol. 15, 1277-94 (1997).
    [CrossRef]
  9. T. Erdogan, "Cladding-mode resonances in short- and long-period fiber gratings filters," J. Opt. Soc. Am. A 14, 1760-1773 (1997); T. Erdogan, "Cladding-mode resonances in short- and long-period fiber grating filters: errata," J. Opt. Soc. Am. A 17, 2113 (2000).
    [CrossRef]
  10. A. W. Snyder and W. R. Young, "Modes of optical waveguides," J. Opt. Soc. Am. 68, 297-309 (1978).
    [CrossRef]
  11. P. Yeh, A. Yariv, and E. Marom, "Theory of Bragg Fiber," J. Opt. Soc. Am. 68, 1196-1201 (1978).
    [CrossRef]
  12. S. Kim, Y. Jeong, S. Kim, J. Kwon, N. Park, and B. Lee, "Control of the characteristics of a long-period grating by cladding etching," Appl. Opt. 39, 2038-2042 (2000).
    [CrossRef]

2005 (3)

2004 (1)

2003 (1)

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

2002 (1)

2000 (1)

1998 (1)

1997 (2)

1978 (2)

Arregui, F. J.

Ashwell, G. J.

Bucholtz, F.

Campopiano, S.

Chung, K. W.

Contessa, L.

Cusano, A.

Cutolo, A.

Del Villar, I.

Erdogan, T.

Heflin, J. R.

Iadicicco, A.

James, S. W.

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristic 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]

Jeong, Y.

Kersey, A. D.

Kim, S.

Kwon, J.

Lee, B.

Marom, E.

Matias, I. R.

Park, N.

Patrick, H. J.

Pilla, P.

Ramachandran, S.

Rees, N. D.

Snyder, A. W.

Stolen, R. H.

Tatam, R. P.

S. W. James and R. P. Tatam, "Optical fiber long-period grating sensors: characteristic 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]

Wang, Z.

Yariv, A.

Yeh, P.

Yin, S.

Young, W. R.

Appl. Opt. (1)

J. Lightwave Technol. (2)

J. Opt. Soc. Am. (2)

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

Meas. Sci. Technol. (1)

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

Opt. Express (2)

Opt. Lett. (3)

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Figures (5)

Fig. 1
Fig. 1

Radial refractive index profile of a structure-modified LPG refractive index sensor.

Fig. 2
Fig. 2

Notch wavelength as the function of the ambient refractive index for the proposed structure-modified LPG sensors with different cladding layer radius r 2.

Fig. 3
Fig. 3

(Color online) (a) Evolution of the azimuthal transverse electric field (E φ) distribution of the HE17 mode at the proximity of the overlay in a structure-modified LPG sensor with different ambient refractive index; (b) transverse electric field distribution of the HE17 mode in LPG. The electric field distribution of the HE16 mode with an ambient refractive 1.0 is shown by dash-dot curves for comparison.

Fig. 4
Fig. 4

(Color online) Notch wavelengths as a function of the ambient refractive index for the HE17 notch of the proposed refractive index sensor (solid curve) and reported LPG refractive index sensors.

Fig. 5
Fig. 5

(Color online) Sensitivity of the HE17 notch of LPG sensor as a function of the ambient refractive index for the proposed LPG sensor (solid curve) and reported LPG refractive index sensors.

Equations (6)

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T 11 1 m = δ 11 1 m α 11 - 1 m 2 sin 2 ( α 11 1 m L ) + cos 2 ( α 11 1 m L ) ,
κ 11 1 m ( z ) = ω 4 0 2 π d ϕ 0 r 1 r d r Δ ε [ E 11 r ( r ) E 1 m r ( r ) + E 11 φ ( r ) E 1 m φ ( r ) ] ,
λ 11 1 m = ( n eff , 11 n eff , 1 m ) Λ ,
T min 11 1 m = 1 sin 2 κ 11 1 m L .
V = 2 π r 2 λ n 2 2 n 4 4 ,
S amb = d λ notch d n amb ,

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