| dc.description.abstract | In this paper, we combine the waveguide mode resonance effect with a surface grating structure called a waveguide grating to design a high figure of merit refractive index sensor. When the incident light is incident on the grating, the diffracted wave will be generated, and the diffracted wave will excite the TE/TM waveguide mode in the waveguide layer, and the mode excited by the grating structure will leak out after propagating for a certain distance. When the phases of the two leaked diffracted waves are matched, resonance will occur.
Using Rsoft Diffrac MOD simulation software to simulate and analyze the one-dimensional waveguide grating structure, and cover the structure with a high refractive index film. After covering the film, the sensitivity reduction decreases by 3.15% from 260.1 to 251.9 (nm/RIU), but because the equivalent refractive index of the grating layer increases, the energy is more concentrated in the structure, while the full width at half maximum ( Full width at half maximum, FWHM) will become narrower, and the FWHM of the TM mode is narrowed from 1.8 × 10-3nm to 3 × 10-4nm, making the narrowed FWHM lower the quality factor (Figure of Merit, FOM). ) increased from 144500 (1/RIU) to 839666 (1/RIU) by 481%.
It can be seen from the electric field diagram that when the structural parameters are changed, due to the increase in the effective refractive index and the orthogonal relationship between the bound mode and the radiation mode, the electric field energy will be dispersed in the structure from the beginning to confined in the effective waveguide transfer between layers. | en_US |