Parametric study of a waveguide Bragg grating filter using coupled mode theory simulation

Designing the waveguide Bragg grating (WBG) filter involves several parameters that determine the filter’s specifications and performance. The refractive index modulation, grating’s period, refractive index of waveguide and cladding, thickness of waveguide will determine the reflected wavelength, intensity and bandwidth. The objective of this project is to find the relationship between the grating’s parameters and their effect on the filter’s performance. The simulation used Optigrating software utilizing the coupled-mode theory. By the end of this simulation, we can classify these parameters into several groups based on their importance. Based on our observation, the refractive index of cladding has also affected the Bragg wavelength and reflection in the WBG filter. The stepper profile of reflecting wavelength versus cladding index change enables the tunable optical devices can be fabricated such as tunable Bragg grating filter and OADM. Moreover, the bandwidth is seemed to be much stable with wide changes. Therefore, the refractive index of the cladding is an alternative to the wavelength tunning element which previously use the refractive index of the core. The results will be a guideline to a researcher in designing Bragg grating for many applications.