arXiv subjects

Brian Gerardot

Publications and source records attributed to Brian Gerardot.

3 recordsLinked to original sources

arXiv2023

Scalable fabrication of hemispherical solid immersion lenses in silicon carbide through grayscale hard-mask lithography

Grayscale lithography allows the creation of micrometer-scale features with spatially-controlled height in a process that is fully compatible with standard lithography. Here, solid immersion lenses are demonstrated in silicon carbide using a novel fabrication protocol combining grayscale lithography and hard-mask techniques to allow nearly hemispherical lenses of 5 $μ$m radius to be etched into the substrate. The technique is highly scalable and compatible with CMOS technology, and device aspect ratios can be tuned after resist patterning by controlling the chemistry of the subsequent dry etch. These results provide a low-cost, high-throughput and industrially-relevant alternative to focused ion beam milling for the creation of high-aspect-ratio, rounded microstructures.

physics.optics↗

arXiv2022

Van der Waals Materials for Applications in Nanophotonics

Numerous optical phenomena and applications have been enabled by nanophotonic structures. Their current fabrication from high refractive index dielectrics, such as silicon or gallium phosphide, pose restricting fabrication challenges, while metals, relying on plasmons and thus exhibiting high ohmic losses, limit the achievable applications. Here, we present an emerging class of layered so-called van der Waals (vdW) crystals as a viable nanophotonics platform. We extract the dielectric response of 11 mechanically exfoliated thin-film (20-200 nm) van der Waals crystals, revealing high refractive indices up to n = 5, pronounced birefringence up to $Δ$n = 3, sharp absorption resonances, and a range of transparency windows from ultraviolet to near-infrared. We then fabricate nanoantennas on SiO$_2$ and gold utilizing the compatibility of vdW thin films with a variety of substrates. We observe pronounced Mie resonances due to the high refractive index contrast on SiO$_2$ leading to a strong exciton-photon coupling regime as well as largely unexplored high-quality-factor, hybrid Mie-plasmon modes on gold. We demonstrate further vdW-material-specific degrees of freedom in fabrication by realizing nanoantennas from stacked twisted crystalline thin-films, enabling control of nonlinear optical properties, and post-fabrication nanostructure transfer, important for nano-optics with sensitive materials.

physics.optics↗

arXiv2016

Structured Beam Generation with a Single Metasurface

Despite a plethora of applications ranging from quantum memories to high-resolution lithography, the current technologies to generate vector vortex beams (VVBs) suffer from less efficient energy use, poor resolution, low damage threshold, bulky size and complicated experimental setup, preventing further practical applications. We propose and experimentally demonstrate an approach to generate VVBs with a single metasurface by locally tailoring phase and transverse polarization distribution. This method features the spin-orbit coupling and the superposition of the converted part with an additional phase pickup and the residual part without a phase change. By maintaining the equal components for the converted part and the residual part, the cylindrically polarized vortex beams carrying orbital angular momentum are experimentally demonstrated based on a single metasurface at subwavelength scale. The proposed approach provides unprecedented freedom in engineering the properties of optical waves with the high-efficiency light utilization and a minimal footprint.

physics.optics↗