Distributed Sensing plays a keyrole in the realm of modern sensing technology and fiber optic sensors are the ultimate choice for that. Fiber optic distributed sensors are extremely popular because it can able to measure strain and temperature difference with very high resolution of about 2 cm. In this paper we have tried to simulate the process of measuring the strains using Stimulated Brillouin and Rayleigh scattering by FDTD method and tried to investigate how well it will match with the strains obtained from the experimental process.These distributed sensors are used to monitor mainly the structural health of the civil or mechanical engineering systems and are facilitate to develop advanced sensing devices like Distributed Acoustic Sensors.

Stimulated Brillouin Scattering, Rayleigh scattering, FDTD, Optical Fiber Sensor, Cross-correlation, Tunable Wavelength Coherence Time Domain Reflectometer (TW-COTDR)

[1]. G.P.Agrawal, Nonlinear Fiber Optics, Academic Press, San Diego, 3rd ed., 2001.
[2]. R. W. Boyd, Nonlinear Optics (Academic, NY, 2003), 2nd ed., Chap. 9.
[3]. Y. Koyamada, M. Imahama, K. Kubota and K.Hogari, "Fiber-optic distributed strain and temperature sensing with very high measurand resolution over long range using coherent OTDR" J. of Lightwave Technology, vol. 27, pp.1142-1146, May 2009.
[4]. M. Froggatt et al., �Correlation and keying of Rayleigh scatter for loss and temperature sensing in parallel optical networks� 2004 OFC Postdeadline Papers, Volume 2, Los Angeles, CA (2004).
[5]. Bao. X. and Chen. L. �Recent Progress in Distributed Fiber Optic Sensors�. Sensors 2012, 12, pp.8601�8639.
[6]. J. B. Cole, N. Okada and S. Banerjee "Advances in Finite Difference Time Domain Methods� Chapter 4: in Light Scattering Reviews, Volume 6, Springer, Berlin, pp. 115-175.
[7]. M. Froggatt, D. Gifford, S. Kreger, M. Wolfe and B. Soller, "Distributed strain and temperature discrimination in unaltered polarization maintaining fiber" in Optical Fiber Sensors, OSA Technical Digest (CD) (Optical Society of America, 2006).
[8]. M. Alahbabi, Y. T. Cho and T. P. Newson, �Comparison of the methods for discriminating temperature and strain in spontaneous Brillouin-based distributed sensors� Optics Letters, vol. 29, no. 1, pp. 26�28, 2004.
[9]. K. Kishida, Y. Yamauchi and A. Guzik, "Study of optical fibers strain-temperature sensitivities using hybrid Brillouin-Rayleigh System" Phot. Sens., vol. 4, no. 1, pp. 1-11, 2014.
[10]. Yu. W. and R. Mittra, "A conformal finite difference time domain technique for modeling curved dielectric surfaces" IEEE Microwave Components Lett., Vol. 11, 2001, pp. 25-27.