Deep‐Subwavelength Focusing and Reflectionless Negative Refraction in Visible‐Light Hyperbolic Metasurface

Abstract Hyperbolic metasurfaces (HMSs) are artificially‐engineered interfaces, exhibiting high anisotropy manifested as hyperbolic dispersion. Their ability to support extremely large momenta with negative diffraction and refraction places them as promising platforms for on‐chip super‐resolution and enhanced light‐matter interaction. While the hyperbolic nature of these structures is experimentally demonstrated, only a limited number of studies have concentrated on their super‐resolution capabilities, which are never obtained at visible‐frequency for fully harnessing their immense resolution potential. Here, a near‐field investigation of visible‐frequency HMSs is presented, exploiting their super‐resolution capabilities to their maximum potential. The impulse response of waves propagating across HMSs is measured and demonstrates deep sub‐wavelength anomalous focusing and on‐chip reflectionless negative refraction at the interface of parabolic and hyperbolic media, independent of incident angle. The approach lays the foundation for sub‐wavelength imaging in 2D space for the advancement of imaging and wave compression devices, leveraging the capabilities of HMSs.