SPR Based Fiber Optic Sensor

SPR base Fiber Optic Sensor Utilizing keen Film of Nickel Kruti Shah and NavneetK. Sharma Department of physics and Materials Science and Engineering,Jaypee Institute of Information Technology, A-10,Sector-62, Noida-201307,India jibe author emailprotectedac.in Abstract.Fiber opthalmic demodulator ground on protrude plasmon ring, employing scale down film of nickel note is presented analytically. Increase in thickness of nickel film results in the enhancement of sensibility of the demodulator. SPR Sensor support by larger-than-life thickness of nickel film possesses maximum aesthesia.INTRODUCTIONSurface plasmon resonance i.e. SPR article of belief has been an important perceptual experience method transgressce hold thirty years. In the beginning, chemical perceptual experience utilizing SPR is demonstrated by Liedberg et al. 1.Collective resounding oscillations of free electrons survive on metal horizontal surface. It produces charge constriction wave move along the metal shape. This charge density wave is transverse wave in nature and is identified as surface plasmon wave. Surface plasmon wave is excited by incident p-polarized clear up. For examining surface plasmon resonance, Kretschmann geometry is exercised 2, 3. Optical case based SPR sensors offer many advantages than middleal prism based SPR sensors 4-6.In the past, lot of research is conducted on optical reference based SPR sensors 7-10. In recent times, nickel (Ni) is shown to let on sensing relevance because of its excellent magnetoelectric machine optical merits 11. Apart from this, Ni is chemically inactive and the cost of Ni is pass up than that of noble metals. Hence, the use of Ni sooner of noble metals decreases the price of SPR sensor. Current bring discusses a SPR based persona optic sensor utilizing thin film of Ni. progeny of thickness of Ni film on the sensitivity of SPR sensor is illustrated. sensitiveness is intensify with the emergence in the thickne ss of Ni film.THEORYSensing system of the sensor contains fiber encumbrance-Ni bed- hear medium. tractile cladding about the core from the of import part of step might multimode PCS fiber is eradicated and is covered with thin horizontal surface of Ni. This layer of Ni is ultimately enclosed by the example medium. Incident light from a white light source is allowed to forecast into one end of the optical fiber and the transmitted light is noticed at the opposite end of the optical fiber.The core of optical fiber is formed by consolidated silica. Refractive index of f apply silica alters with wavelength as, 23 22322 22221 22111b ab ab a) ( n? +? +? + = (1) Here, ? is the wavelength of incident light in m and a1, a2, a3, b1, b2 and b3 atomic number 18 Sellmeier coefficients. The values of coefficients, used in (1) are specified as, a1 = 0.6961663, a2 = 0.4079426, a3 = 0.8974794, b1 = 0.0684043 m, b2 = 0.1162414 m and b3 = 9.896161 m 12.The dielectric unending of a metal do-n othing be mentioned as, ) ( 1 ) (22? ? ? ? ?i ic pcmi mr m+ ? = + = (2) Where, ?p and ?c are plasma and impact wavelengths of the metal respectively. For, Ni p?= 2.5381 x 10-7 m andc?= 2.8409 x 10-5 m. Also, the dielectric constant of sample medium is written as,2s sn =? where, sn is refractile index of the sample medium. Resonance condition for the surface plasmon wave is written as, K Re sin nsp=12 (3) Here, 2 22s ms ms ms mspn nc K+ =+ =? is the wave vector of surface plasmon wave and c is the amphetamine of light in vacuum. Reflection coefficient of p-polarized light is calculated by using intercellular substance method 13.Normalized transmitted power from the sensor is computed as 14. Further, the sensitivity of sensor can be described as pitch in resonance wavelength per unit diversity in refractive index of sample medium 15. RESULTS AND DISCUSSION For simulation, refractive index of sample medium is presumed to be altered from 1.33 to 1.37. Values of various para meters used are mentioned as fibers numerical aperture = 0.24, core diam of fiber = 600 m and exposed sensing region length = 15 mm. contractable power from the sensor is measured for diametric thicknesses (20 nm-80 nm) of Ni layer and consequent resonance wavelengths are measured. Resonance wavelengths for different thicknesses sum up linearly with increase in the refractive index of the sample medium. 20 40 60 80 0 15003000 4500 6000 7500Sensitivity (nm/RIU)Thickness of Ni layer (nm) FIGURE 1. Variation of sensitivity with thickness of Ni layer. Figure 1 represents the variation of sensitivity with Ni layer thickness.Ni layer thickness is increase from 20 nm to 80 nm. Sensitivity is exaggerated with increase in Ni layer thickness. The reason for this enhancement in sensitivity is ascribed to high value of truly part of dielectric constant of Ni. accordingly for a fixed change in refractive index of sample medium, Ni enhances the shift between resonance wavelengths. This resul ts in enhanced sensitivity of sensor with increase in Ni layer thickness.Thus, large Ni layer thickness leads in high sensitivity of SPR based sensor.CONCLUSIONS notional analysis of SPR based fiber optic sensor with thin layer of Ni is carried out. Sensitivity of SPR based sensor is enlarged with increase in Ni layer thickness. In order to achieve highest sensitivity of the sensor, large thickness of Ni layer is advised. ACKNOWLEDGEMENTS Navneet K. Sharma wishes to thank Defence Research using Organization (DRDO), India for the financial grant provided done the project number ERIP/ER/DG-ECS/990116205/M/01/1687.REFERENCESB. Liedberg, C. Nylander and I. Sundstrom, Sens. Actuat. B 4, 299-304 (1983).R. D. Harris and J. S. Wilkinson, Sens. Actuat. B 29, 261-267 (1995).E. Kretschmann and H. Reather, Zeits. Natur. 23, 2135-2136 (1968).J. Homola, Sens. Actuat. B 29, 401-405 (1995). 5. W. B. Lin, N. Jaffrezic-Renault, A. Gagnaire and H. Gagnaire, Sens. Actuat. A 84, 198-204 (2000).A. K. Sharma and B. D. Gupta, Sens. Actuat. B 100, 423-431 (2004).S. Singh, S. K. Mishra and B. D. Gupta, Sens. Actuat. A 193, 136-140 (2013).N. K. Sharma, M. Rani, and V. Sajal, Sens. Actuat. B 188, 326-333 (2013).S. Shukla, M. Rani, N. K. Sharma and V. Sajal, Opt. 126, 4636-4639 (2015).S. Shukla, N. K. Sharma and V. Sajal, Sens. Actuat. B 206, 463-470 (2015).S. Shukla, N. K. Sharma and V. Sajal, Braz. J. Phy. 46, 288-293 (2016).A. K. Ghatak and K. Thyagarajan, An Introduction To Fiber Optics(Cambridge University Press, Cambridge, 1999), pp. 82-83.K. Sharma and B. D. Gupta, J. Appl. Phys. 101, 093111 (2007).B. D. Gupta, A. Sharma and C. D. Singh, Int. J. Optoelectron. 8, 409-418 (1993). 15. A. K. Sharma and B. D. Gupta, Opt. Commun. 245, 159-169 (2005).