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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 5 — Mar. 11, 2013
  • pp: 6313–6320

Effect of coating thickness on the sensitivity of a humidity sensor based on an Agarose coated photonic crystal fiber interferometer

Jinesh Mathew, Yuliya Semenova, and Gerald Farrell  »View Author Affiliations

Optics Express, Vol. 21, Issue 5, pp. 6313-6320 (2013)

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We report the effect of coating thickness on the sensitivity of a relative humidity (RH) sensor based on an Agarose coated photonic crystal fiber interferometer for the first time. An experimental method is demonstrated to select an optimum coating thickness to achieve the highest sensitivity for a given RH sensing range. It is shown that the Refractive Index (RI) of the coating experienced by the mode interacting with the coating depends on the thickness of the coating. It is observed that the spectral shift of the interferometer depends on both the bulk RI change and the thickness change of the Agarose coating with respect to an RH change. The RH sensitivity of the sensor has a significant dependence on the thickness of the coating and the sensor with highest sensitivity shows a linear response for RH change in the range of 40-90% RH with a humidity resolution of 0.07%RH and a fast response time of 75 ms for an RH change from 50% to 90%.

© 2013 OSA

OCIS Codes
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(310.0310) Thin films : Thin films
(060.5295) Fiber optics and optical communications : Photonic crystal fibers

ToC Category:

Original Manuscript: October 23, 2012
Revised Manuscript: October 24, 2012
Manuscript Accepted: December 5, 2012
Published: March 6, 2013

Jinesh Mathew, Yuliya Semenova, and Gerald Farrell, "Effect of coating thickness on the sensitivity of a humidity sensor based on an Agarose coated photonic crystal fiber interferometer," Opt. Express 21, 6313-6320 (2013)

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  1. T. L. Yeo, T. Sun, and K. T. V. Grattan, “Fibre-optic sensor technologies for humidity and moisture measurement,” Sens. Actuators A Phys.144(2), 280–295 (2008). [CrossRef]
  2. J. Mathew, Y. Semenova, G. Rajan, P. Wang, and G. Farrell, “Improving the sensitivity of a humidity sensor based on fiber bend coated with a hygroscopic coating,” Opt. Laser Technol.43(7), 1301–1305 (2011). [CrossRef]
  3. J. Mathew, Y. Semenova, and G. Farrell, “A fiber bend based humidity sensor with a wide linear range and fast measurement speed,” Sens. Actuators A Phys.174, 47–51 (2012). [CrossRef]
  4. J. Mathew, K. J. Thomas, V. P. N. Nampoori, and P. Radhakrishnan, “A comparative study of fiber optic humidity sensors based on chitosan and agarose,” Sens. Transducers J.84, 1633–1640 (2007).
  5. H. Y. Choi, M. J. Kim, and B. H. Lee, “All-fiber Mach-Zehnder type interferometers formed in photonic crystal fiber,” Opt. Express15(9), 5711–5720 (2007). [CrossRef] [PubMed]
  6. R. Jha, J. Villatoro, and G. Badenes, “Ultrastable in reflection photonic crystal fiber modal interferometer for accurate refractive index sensing,” Appl. Phys. Lett.93(19), 191106 (2008). [CrossRef]
  7. J. Mathew, Y. Semenova, G. Rajan, and G. Farrell, “Humidity sensor based on photonic crystal fibre interferometer,” Electron. Lett.46(19), 1341–1343 (2010). [CrossRef]
  8. J. Mathew, Y. Semenova, and G. Farrell, “Photonic crystal fiber interferometer for dew detection,” J. Lightwave Technol.30(8), 1150–1155 (2012). [CrossRef]
  9. J. Mathew, Y. Semenova, and G. Farrell, “Relative humidity sensor based on an agarose infiltrated photonic crystal fiber interferometer,” IEEE J. Sel. Top. Quantum Electron.18(5), 1553–1559 (2012). [CrossRef]
  10. J. Villatoro, V. Finazzi, V. P. Minkovich, V. Pruneri, and G. Badenes, “Temperature-insensitive photonic crystal fiber interferometer for absolute strain sensing,” Appl. Phys. Lett.91(9), 091109 (2007). [CrossRef]
  11. D. Barrera, J. Villatoro, V. P. Finazzi, G. A. Cardenas-Sevilla, V. P. Minkovich, S. Sales, and V. Pruneri, “Low-loss photonic crystal fiber interferometers for sensor networks,” J. Lightwave Technol.28(24), 3542–3547 (2010). [CrossRef]
  12. R. Jha, J. Villatoro, G. Badenes, and V. Pruneri, “Refractometry based on a photonic crystal fiber interferometer,” Opt. Lett.34(5), 617–619 (2009). [CrossRef] [PubMed]
  13. M. Smietana, D. Brabant, W. J. Bock, P. Mikulic, and T. Eftimov, “Refractive-index sensing with inline core-cladding intermodal interferometer based on silicon nitride nano-coated photonic crystal fiber,” J. Lightwave Technol.30(8), 1185–1189 (2012). [CrossRef]
  14. J. Mathew, Y. Semenova, and G. Farrell, “Polymer coated photonics crystal fiber interferometer for relative humidity sensing,” A. Ghosh, and D. Choudhury (Eds.): Proc. IConTOP–II, pp. 73–78, (2011).
  15. F. J. Arregui, Z. Ciaurriz, M. Oneca, and I. R. Matías, “An experimental study about hydrogels for the fabrication of optical fiber humidity sensors,” Sens. Actuators B Chem.96(1-2), 165–172 (2003). [CrossRef]
  16. K. J. Lee, D. Wawro, P. S. Priambodo, and R. Magnusson, “Agarose-gel based guided-mode resonance humidity sensor,” IEEE Sens. J.7(3), 409–414 (2007). [CrossRef]
  17. C. Bariáin, I. R. Matías, F. J. Arregui, and M. López-Amo, “Optical fiber humidity sensor based on a tapered fiber coated with agarose gel,” Sens. Actuators B Chem.69(1-2), 127–131 (2000). [CrossRef]
  18. M. Hernaez, C. R. Zamarreño, C. Fernandez-Valdivielso, I. del Villar, F. J. Arregui, and I. R. Matias, “Agarose optical fibre humidity sensor based on electromagnetic resonance in the infra-red region,” Phys. Status Solidi C7(11-12), 2767–2769 (2010). [CrossRef]
  19. J. J. Roberts, A. Earnshaw, V. L. Ferguson, and S. J. Bryant, “Comparative study of the viscoelastic mechanical behavior of agarose and poly(ethylene glycol) hydrogels,” J. Biomed. Mater. Res. B Appl. Biomater.99B(1), 158–169 (2011). [CrossRef] [PubMed]
  20. I. Del Villar, I. R. Matías, F. J. Arregui, and P. Lalanne, “Optimization of sensitivity in long period fiber gratings with overlay deposition,” Opt. Express13(1), 56–69 (2005). [CrossRef] [PubMed]
  21. J. Lu, Z. Chen, F. Pang, and T. Wang, “Theoretical analysis of fiber-optic evanescent wave sensors,” in Proceedings of IEEE Microwave Conference, (China-Japan Joint, 2008), pp.583–587, doi: 10.1109/CJMW.2008.4772500. [CrossRef]
  22. S. T. Lee, P. S. Kumar, K. P. Unnikrishnan, V. P. N. Nampoori, C. P. G. Vallabhan, S. Sugunan, and P. Radhakrishnan, “Evanescent wave fibre optic sensors for trace analysis of Fe3+ in water,” Meas. Sci. Technol.14(6), 858–861 (2003). [CrossRef]

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