Quadratic meta-reflectors made of HFO2 nanopillars with a large field of view at infrared wavelengths

Abstract

Metasurfaces, being composed of subwavelength nanostructures, can achieve peculiar optical manipulations of phase, amplitude, etc. A large field of view (FOV) is always one of the most desirable characteristics of optical systems. In this study, metasurface-based quadratic reflectors (i.e., meta-reflectors) made of HfO2 nanopillars are investigated to realize a large FOV at infrared wavelengths. First, the geometrical dependence of HfO2 nanopillars’ phase difference is analyzed to show the general principles of designing infrared HfO2 metasurfaces. Then, two meta-reflectors with a quadratic phase profile are investigated to show their large FOV, subwavelength resolution, and long focal depth. Furthermore, the two quadratic reflectors also show a large FOV when deflecting a laser beam with a deflecting-angle range of approximately ±80◦ . This study presents a flat optical metamaterial with a large FOV for imaging and deflecting, which can greatly simplify the optical–mechanical complexity of infrared systems, particularly with potential applications in high-power optical systems.