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High performance optical elements and devices based on dielectric metasurface

Optical elements and devices based on metallic metasurface, with periodic micronano structures sitting on a substrate, have advantages such as ultra-thinness, broadband response and large extending angles. However, the relatively low efficiency is still a big problem and would hold back their practical applications. Though high performance metasurface devices such as hologram with 80% optical efficiency have been reported recently [1], the intrinsic ohmic losses cannot be avoided still now. In this paper, we present that silicon nanobrick arrays (a typical dielectric metasurface), with their anisotropic nano-structures, is sensitive to the polarisation of an incident beam and can be used to form high performance elements and devices. With careful design of such structures in the fiber telecommunications windows (1460nm ~ 1625 nm), magnetic resonance occurs along the long axis direction and light with polarization aligned with this direction would be almost totally reflected (~ 98.5%), whilst that along the short axis is nearly totally transmitted (~ 94.3%). That implies that a novel polarising beam splitter (PBS) can be formed with silicon nanobrick arrays. The silicon nanobrick-based PBS can find applications in photonic integrated circuits (PICs) since an ultra-compact PBS is always required to be integrated into a multifunctional optoelectronic device.