The characterization of Fiber Bragg grating such as strain, Bragg wavelength shift, spectral response and its
bandwidth are provided and also discussed by means of its parameter setup namely effective refractive index, Bragg wavelength,
grating period and strain-optic constant with varying the grating length and refractive index change. Analyzing and obtaining
the data works are referred based on the coupled mode equations. In this paper, FBG spectral responses are simulated through
the help of a high -level programming language such as GNU Octave software.