Numerical examination on transmission properties of FBG by FDTD method

Fiber Bragg grating (FBG) is one of important component in optical system as band reject filter. It could act as a sensor also in engineering area. It is important to examine the design of FBG both in optical systems and in sensor regions. Finite difference time domain (FDTD) method is used to simulate FBG and evaluate the transmission properties. FBG here is simulated as two-dimensional periodic waveguide structures for single mode only. Higher grating refractive index value affect in smaller value of transmission in specific wavelength, and the center wavelength drop is shifted to higher value. Increasing grating period will affect to the output shifting to higher wavelength value with a linear correlation. Longer grating length will reduce the transmission value with linear correlation between them. Chirped FBG (CFBG) show a weaker reflectance, but with wider broadband wavelength reflected. Higher temperature will result in wavelength shift to the higher wavelength value, with a linear correlation between them.