# Infrared All-Dielectric Metasurface Beam Splitter Based on Transflective Structures
## 3 Simulation Results
In order to further visualize the variation of the outgoing light at an incidence angle of 16\({}^{\circ}\), we calculated the light field intensity distribution in the X\(-\)Y plane parallel to the reflective end of the metasurface at 0\({}^{\circ}\) and 16\({}^{\circ}\) incidence angles, respectively, and the final results are shown in Figure 2:1 It can be seen that at 0\({}^{\circ}\), the reflective end basically behaves as a deflected outgoing light subject to phase modulation. Furthermore, at 16\({}^{\circ}\), the modulated outgoing light disappears, and the reflective end completely behaves as directly reflected light from the metasurface substrate. The simulation results show that the metasurface beam splitter has a large operating angle bandwidth of about 32\({}^{\circ}\) and that the deflection angle of the beam splitter does not change significantly with the incident angle, expressing strong operating stability. Based on the planar distribution (like Figure 10) of the light field intensity at the maximum of the double-ended light field intensity and the light field intensity distribution near the point of the maximum intensity (like Figure 8), we can calculate the energy not involved in the deflected beam-splitting. The result is 6.7%, so the total splitting efficiency is 93.3%. Table 2 summarizes some representative data for the diffraction efficiency of previous reports, including reflective and transmissive metasurface-based BSs (RMBS and TMBS). Compared to previous reports, our design achieves a similar theoretical TES value with a  
Figure 2:2 (**a**) The normalized intensity distribution of the light field in the X\(-\)Y plane when the incident light angle is 0\({}^{\circ}\) has a clear phenomenon of deflection out to the positive \(y\)-axis at the transmissive end. (**b**) The normalized intensity distribution of the light field in the X\(-\)Y plane when the incident light angle is 16\({}^{\circ}\); the reflective end completely behaves as directly reflected light from the metasurface substrate. Figure 2:3 (**a**) Phase diagram of the Y\(-\)Z plane at the reflective end of the metasurface under 16\({}^{\circ}\) incidence of 1.55 μm x-line polarized light. The influence of the isophase tilt is no longer apparent. (**b**) Phase diagram of the metasurface’s transmissive end Y\(-\)Z plane under a 16\({}^{\circ}\) incidence of 1.55 μm x-line polarized light. simpler structure, and the structural advantages of the transverse metasurface beam splitter are demonstrated to a certain extent. To verify the above results, we also performed numerical simulation using the Finite Integration Technique (FIT) method and compared the decisive results obtained (as shown in Appendix A) with the FDTD method simulation results. Similar unit cell transmittance and phase variation curves indicate that the complete metasurface composed and characterized by unit cell structures should also have similar operating properties, which is confirmed by the similar metasurface double-ended isophase plane distribution. Therefore, we believe that the simulation comparison results in Appendix A can validate the correctness of the results in this paper. In our tentative idea, the Si film grows on top of the whole SiO\({}_{2}\) region by chemical vapor deposition (CVD). After spin-coating a layer of negative resist on the sample, electron-beam lithography (EBL) directly draws the patterns with nanoscale featured sizes and is followed by induced coupled plasma (ICP) silicon etching. Finally, when the remaining resist is cleared by the lift-off process, the designed transflective metasurface beam splitter is completed.