Infrared all-dielectric bifocal metasurface beam splitter based on the transflective structure

Based on the design concept of a transflective double-ended response structured metasurface and the Pancharatnam-Berry (PB) phase modulation mechanism, we have designed and numerically demonstrated a bifocal all-dielectric metasurface beam splitter. This device is constructed by arranging silicon nanocolumns on SiO2 substrates. The bifocal metasurface beam splitter developed in this study achieves double-ended deflected focusing beam splitting at a wavelength of 1.55 mu m. The focusing efficiency at both ends exceeds 50%, the equivalent numerical aperture at both ends is greater than 0.85, and the beam splitting ratio is approximately 1.4:1. Furthermore, compared to most current single-ended response bifocal metasurfaces, the transflective bifocal metasurface beam splitter, with equal phase modulation at both ends, is anticipated to be integrated into compact optical systems that require real-time signal feedback.