RESUMO
High-index dielectric metasurfaces featuring Mie-type electric and magnetic resonances have been of great interest in a variety of applications such as imaging, sensing, photovoltaics, and others, which led to the necessity of an efficient large-scale fabrication technique. To address this, here we demonstrate the use of single-pulse laser interference for direct patterning of an amorphous silicon film into an array of Mie resonators a few hundred nanometers in diameter. The proposed technique is based on laser-interference-induced dewetting. A precise control of the laser pulse energy enables the fabrication of ordered dielectric metasurfaces in areas spanning tens of micrometers and consisting of thousands of hemispherical nanoparticles with a single laser shot. The fabricated nanoparticles exhibit a wavelength-dependent optical response with a strong electric dipole signature. Variation of the predeposited silicon film thickness allows tailoring of the resonances in the targeted visible and infrared spectral ranges. Such direct and high-throughput fabrication is a step toward a simple realization of spatially invariant metasurface-based devices.
RESUMO
A superoscillatory lens (SOL) is known to produce a sub-diffraction hotspot that is useful for high-resolution imaging. SOLs have not yet been directly used in a confocal reflection setup, as the SOL suffers from poor imaging properties. Additionally, the illuminating intensity distribution of the SOL still has high-intensity rings called sidelobes coexisting with the central hotspot. By means of a reflection setup, which does not have the SOL in the detection chain, thereby mitigating the poor imaging properties, we assessed the resolution capabilities of a SOL. This was done for different objects, whose dimensions were both above and below the SOL field-of-view (FOV). We found that the sidelobe illumination degrades the imaging properties in the case of extended objects, limiting the applicability of a SOL system.
