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.
Highlights
In recent years, 2D metamaterials, i.e., metasurfaces, have emerged as a promising alternative to traditional bulky optical components [1,2,3,4], achieving miniature optical systems with many peculiar properties
Researchers have demonstrated an array of high-performance all-dielectric metasurfaces, paving the way for metamaterials towards multi-functional compacted optical systems
HfO2 metasurfaces made of refractory materials HfO2 with a large field of view at infrared wavelengths is very desired for high-power optical systems, which can be employed to direct or collect high-power light beams with a large FOV
Summary
2D metamaterials, i.e., metasurfaces, have emerged as a promising alternative to traditional bulky optical components [1,2,3,4], achieving miniature optical systems with many peculiar properties. A metallic metasurface with a quadratic phase profile realized a wide range of operation angles [31]. These works are based on non-refractory materials for the non-high-power systems. For the applications in the high-power systems, the refractory materials should be employed to construct metasurfaces. HfO2 metasurfaces made of refractory materials HfO2 with a large field of view at infrared wavelengths is very desired for high-power optical systems, which can be employed to direct or collect high-power light beams with a large FOV. Two meta-reflectors are constructed following a quadratic phase profile, and their optical properties of the FOV, resolution, and focal depth are researched when focusing light beam. The investigation is not reported in the previous literature
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