Optimal thickness of TiO2 layer on resonance waveguide grating for maximum of electric field by simulation method in comparison with experiment

Abstract

Resonant waveguide grating (RWG) is one of the important devices in optics. Not only was it used as light dispersion equipment, but also RWG was used to enhance the intensity of the electric field on the surface of the device. Some parameters influence to electric field distribution of RWG such as the refractive index of the layers of RWG, the thickness of the layers, the depth of the grating, the period of the grating, and the wavelength of the incident light. In this work, the thickness of the TiO₂ layer on the surface of the RWG was changed while all of the other parameters were fixed. The distribution of the electric field was calculated and the resonant angle was found at the different thicknesses of the TiO₂ layer. The results show that the optimal thickness of the TiO₂ layer is 50 nm at the excitation wavelength of 793 nm. Changing the electric field intensity versus TiO₂ thickness will be discussed in detail. The real RWG was fabricated based on the simulation results for the high transmittance at the wavelength of 793 nm.