Proposed method of three-channel division by covered multilayer model

In this paper, a triple-layer grating splitter with three-port output is designed. Under normal incidence of light at 800 nm wavelength, the diffraction efficiency of 0th order and +/- 1st orders under TE polarization are 32.87% and 32.86%, respectively. The diffraction efficiency of 0th order and +/- 1st orders under TM polarization are 31.98%, respectively. The results show that the total diffraction efficiency is more than 95% under TE polarization and TM polarization. Through the combination of rigorous coupled-wave analysis (RCWA) and simulated annealing algorithms (SAA), the calculation and optimization of each parameter of the grating is carried out to make the diffraction efficiency of the grating meet the conditions. Finally, the effects of incident wave characteristics and grating parameters on diffraction efficiency are discussed.