Metasurfaces and Colloidal Suspensions Composed of 3D Chiral Si Nanoresonators

Abstract

High-refractive-index silicon nanoresonators are promising low-loss alternatives to plasmonic particles in CMOS-compatible nanophotonics applications. However, complex 3D particle morphologies are challenging to realize in practice, thus limiting the range of achievable optical functionalities. Using 3D film structuring and a novel gradient mask transfer technique, the first intrinsically chiral dielectric metasurface is fabricated in the form of a monolayer of twisted silicon nanocrescents that can be easily detached and dissolved into colloidal suspension. The metasurfaces exhibit selective handedness and a circular dichroism as large as 160° µm due to pronounced differences in induced current loops for left-handed and right-handed polarization. The detailed morphology of the detached particles is analyzed using high-resolution transmission electron microscopy. Furthermore, it is shown that the particles can be manipulated in solution using optical tweezers. The fabrication and detachment method can be extended to different nanoparticle geometries and paves the way for a wide range of novel nanophotonic experiments and applications of high-index dielectrics.

Circular dichroism mode splitting and bounds to its enhancement with cavity-plasmon-polaritons

“…To that end, we have fabricated chiral gold nanocrescents using hole-mask colloidal lithography using techniques described in refs. 33,35 (see Appendix D for further details). Fig.…”

“…In order to test the analytical predictions, we perform a proof-of-principle experiment and the corresponding FDTD simulations with a coupled chiral nanoparticles-cavity system (see Appendix B for details of simulations). To ensure strong interaction of the chiral scatterer with the cavity, we will use chiral plasmonic nanocrescents [33][34][35] instead of molecules due to their large oscillator strength. Fig.…”

Low‐Loss Hybrid High‐Index Dielectric Particles on a Mirror for Extreme Light Confinement

“…Recently our group had developed a novel fabrication technique that is able to produce HID nanostructures with nearly any desired shape/size, while maintaining high‐quality crystalline quality of the material and therefore low absorptive losses in the red region of the visible spectrum. This fabrication technique is described in further detail in Section , “Fabrication.” Essentially, the method uses a high‐quality poly‐Si film, and the desired nanoparticles are etched from this film. The newly created Si nanoparticles are then removed from the substrate and dispersed into a colloidal solution.…”

“…This fabrication technique is described in further detail in Section 2, "Fabrication." [39,40] Essentially, the method uses a highquality poly-Si film, and the desired nanoparticles are etched from this film. The newly created Si nanoparticles are then removed from the substrate and dispersed into a colloidal solution.…”

Direct Imprinting of Quasi‐3D Nanophotonic Structures into Colloidal Quantum‐Dot Devices

“…To reach a new degree of freedom of light manipulation, nanophotonic structures have been gradually upgraded from two-dimensional (2D) into the three-dimensional (3D) regime. [9][10][11] Imprinting is a known method to create 2D or 3D nanostructures in photoresists, polymers, and metals, which can flow under pressure and heat. [12] While this might not be expected to work with CQD films which are granular solids, we demonstrate here that optically functional quasi-3D nanostructures can be directly imprinted into solid-state CQD films without altering key materials properties such as carrier mobility, doping, and energy gap, because the imprinting process involves no modification of the interfacial chemistry of CQDs.This will be a valuable addition to the array of state-of-art nanofabrication techniques like laser writing, focused ion beam writing, [13] and electron-beam lithography.…”