Ultrahigh-reflectivity chiral mirrors based on the metasurface of the quarter-waveplate

A study is conducted on a GaAs-based high-contrast subwavelength chiral metasurface (HCCM) designed for 1064 nm. The metasurface integrates a high-contrast subwavelength grating (HCG) for TM mode modulation, a SiO₂ support layer, and a compact quarter-waveplate (QWP) to convert linearly polarized light to circularly polarized light. The HCG achieves ultra-high reflectivity at 1064 nm, attributed to the large refractive index contrast between the Si grating and SiO2 layer. The designed HCCM has a reflectivity of more than 99 % for the TM mode and less than 80 % for the TE waves in the wavelength range of 1050 nm-1085nm, and it can also excite the circularly polarized light with an absolute error of less than 0.03 at the transmitting end in the case of the 1064 nm TM wavelength. These results suggest that circular dichroic metasurfaces could offer a promising approach for photonic manipulation in circular polarization VCSELs, potentially reducing the manufacturing challenges and costs associated with traditional methods.