New control scheme for four-port grating beam splitter with HfO₂ layer

In this paper, a transmission four-port grating beam splitter with Oth order rejection is proposed. Under normal incident conditions, the grating parameters were optimized using rigorous coupled wave analysis and simulated annealing algorithm, and the diffraction efficiency of the optimized grating is 24.24% and 24.34% for the +/- 1st and +/- 2nd orders under transverse electric polarization, respectively, and 24.16% and 23.21% for the 1st and 2nd orders under transverse magnetic polarization. In addition, the electric field distribution of the grating was analyzed using the finite element method, and the diffraction phenomenon of the grating was analyzed using the simplified modal method. Most importantly, the grating has good polarization-independent spectral performance. The data show that the grating structure has high processing tolerance and is advantageous in the field of beam splitters.