This paper presents the research made at the Laboratory of Optics, Lasers and Systems (LOLS) of the Faculty of Sciences of University of Lisbon, Portugal, in the field of fiber-based sensors. Three areas are considered: sensor encapsulation for natural aqueous environments, refractive index modulation and laser micropatterning. We present the main conclusions on the issues and parameters to take in consideration for the encapsulation process and results of its design and application. Mid-infrared laser radiation was applied to produce long period fiber gratings and nanosecond pulses of near-infrared Q-switch laser were used for micropatterning.
References
[1]
Silva, C.; Coelho, J.; Caldas, P.; Fraz？o, O.; Jorge, P. Santos optical fiber sensing system based on long-period gratings for remote refractive index measurement in aqueous environments. Fiber Integr. Opt 2010, 29, 160–169, doi:10.1080/01468031003759493.
[2]
Silva, C.; Coelho, J.M.; Caldas, P.; Jorge, P. Fibre Sensing System Based on Long-Period Gratings for Monitoring Aqueous Environments. In Fiber Optic Sensors; Yasin, M., Harun, S., Arof, H., Eds.; InTech: Lexington, KY, USA, 2012. Chapter 13,; pp. 317–342.
Chiang, C.-C.; Tsai, L. Perfectly notched long-period fiber grating filter based on ICP dry etching technique. Opt. Lett 2012, 37, 193–195, doi:10.1364/OL.37.000193. 22854464
[5]
Rego, G.; Okhotnikov, O.; Dianov, E.; Sulimov, V. High-temperature stability of long-period fiber gratings produced using an electric arc. J. Lightwave Technol 2001, 19, doi:10.1109/50.956145.
[6]
Wang, Y. Review of long period fiber gratings written by CO2 laser. J. Appl. Phys 2010, 108, 081101:1–081101:18.
[7]
Davis, D.D.; Gaylord, T.K.; Glytis, E.N.; Kosinski, S.G.; Mettler, S.C.; Vengsarkar, A.M. Long period fibre grating fabrication with focused CO2 laser pulses. Electron. Lett 1998, 34, 302–303, doi:10.1049/el:19980239.
[8]
Oh, S.T.; Han, W.T.; Paek, U.C.; Chung, Y. Azimuthally symmetric long-period fiber gratings fabricated with CO2 laser. Microw. Opt. Technol. Lett 2004, 41, 188–190, doi:10.1002/mop.20088.
[9]
Su, L.; Chiang, K.S.; Lu, C. CO2-laser-induced long-period gratings in graded-index multimode fibers for sensor applications. IEEE Photonics Technol. Lett 2006, 18, 190–192, doi:10.1109/LPT.2005.861267.
[10]
Zhu, T.; Chiang, K.; Rao, Y.; Shi, C.; Song, Y.; Liu, M. Characterization of long-period fiber gratings written by CO2 laser in twisted single-mode fibers. J. Lightwave Technol 2009, 27, 4863–4869, doi:10.1109/JLT.2009.2029542.
[11]
Harp, W.; Paleocrassas, A.; Tu, J. A practical method for determining the beam profile near the focal spot. Int. J. Adv. Manuf. Technol 2008, 37, 1113–1119, doi:10.1007/s00170-007-1067-z.
[12]
Wang, Y.-P.; Wang, D.N.; Jin, W.; Rao, Y.-J.; Peng, G.-D. Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber. Appl. Phys. Lett 2006, 89, 151105:1–151105:3.
Wei, T.; Han, Y.; Li, Y.; Tsai, H.-L.; Xiao, H. Temperature-insensitive miniaturized fiber inline Fabry-Perot interferometer for highly sensitive refractive index measurement. Opt. Express 2008, 16, 5764–5769, doi:10.1364/OE.16.005764. 18542685
[15]
Tafulo, P.; Fraz？o, O.; Jorge, P.A.S.; Araújo, F.M. Intrinsic Fabry-Perot cavity sensor based on chemical etching of a multimode graded index fiber spliced to a single mode fiber. Proc. SPIE 2010, 7653, doi:10.1117/12.866336.
Claus, R.O.; Gunther, M.F.; Wang, A.; Murphy, K.A. Extrinsic Fabry-Perot sensor for strain and crack opening displacement measurements from 200 °C to 900 °C. Smart Mater. Struct 1992, 1, 237–242, doi:10.1088/0964-1726/1/3/008.
[18]
Choi, H.Y.; Park, K.S.; Park, S.J.; Paek, U.; Lee, B.H.; Choi, E.S. Miniature fiber-optic high temperature sensor based on a hybrid structured Fabry-Perot interferometer. Opt. Lett 2008, 33, 2455–2457, doi:10.1364/OL.33.002455. 18978885
[19]
Gupta, B.D.; Verma, R.K. Surface plasmon resonance-based fiber optic sensors: Principle, probe designs, and some applications. J. Sens 2009, 2009, doi:10.1155/2009/979761.
[20]
Hassani, A.; Skorobogatiy, M. Design criteria for microstructured-optical-fiber based surface-plasmon-resonance sensors. J. Opt. Soc. Am. B 2007, 24, 1423–1429, doi:10.1364/JOSAB.24.001423.
Wei, T.; Han, Y.; Tsai, H.-L.; Xiao, H. Miniaturized fiber inline Fabry-Perot interferometer fabricated with femtosecond laser. Opt. Lett 2008, 33, 536–538, doi:10.1364/OL.33.000536. 18347701
[24]
Rao, Y.; Deng, M.; Duan, D.-W.; Yang, X.-C.; Zhu, T.; Cheng, G.-H. Micro Fabry-Perot interferometers in silica fibers machined by femtosecond laser. Opt. Express 2007, 15, 14123–14128, doi:10.1364/OE.15.014123. 19550685
[25]
Silva, C.; Coelho, J.M.; Ruivo, A.; de Matos, A.P. Infrared nanosecond laser effects on the formation of copper nanoparticles. Mater. Lett 2010, 64, 705–707, doi:10.1016/j.matlet.2009.12.044.
[26]
Coelho, J.M.; Silva, C.; Ruivo, A.; Botelho, M.L.; de Matos, A.P. Local laser-decolorizing of Gamma-ray irradiated silicate glass. Opt. Eng 2011, 50, doi:10.1117/1.3591948.
[27]
Nespereira, M.; Silva, C.; Coelho, J.; Rebord？o, J. Nanosecond laser micropatterning of optical fibers. Proc. SPIE 2011, 8001, doi:10.1117/12.892087.
[28]
Coelho, J.M.; Silva, C.; Ruivo, A.; de Matos, A.P. Infrared Nanosecond Laser Radiation in the Creation of Gold and Copper Nanoparticles. Book of Abstracts, VI International Materials Symposium, MATERIAIS 2011, Guimar？es, Portugal, 18–20 April 2011; p. 340.
