Third Harmonic Generation Enhancement and Wavefront Control Using a Local High- Metasurface.

High quality factor optical nanostructures provide a great opportunity to enhance nonlinear optical processes such as third harmonic generation. However, the field enhancement in these high quality factor structures is typically accompanied by optical mode nonlocality. As a result, the enhancement of nonlinear processes comes at the cost of their local control as needed for nonlinear wavefront shaping, imaging, and holography.

High quality factor metasurfaces for two-dimensional wavefront manipulation.

The strong interaction of light with micro- and nanostructures plays a critical role in optical sensing, nonlinear optics, active optical devices, and quantum optics. However, for wavefront shaping, the required local control over light at a subwavelength scale limits this interaction, typically leading to low-quality-factor optical devices. Here, we demonstrate an avenue towards high-quality-factor wavefront shaping in two spatial dimensions based on all-dielectric higher-order Mie-resonant metasurfaces.

Excitonic Beam Steering in an Active van der Waals Metasurface.

Two-dimensional transition metal dichalcogenides (2D TMDCs) are promising candidates for ultrathin active nanophotonic elements due to the strong tunable excitonic resonances that dominate their optical response. Here, we demonstrate dynamic beam steering by an active van der Waals metasurface that leverages large complex refractive index tunability near excitonic resonances in monolayer molybdenum diselenide (MoSe). Through varying the radiative and nonradiative rates of the excitons, we can dynamically control both the reflection amplitude and phase profiles, resulting in an excitonic phased array metasurface.

Refractive Index Modulation in Monolayer Molybdenum Diselenide.

Two-dimensional transition metal dichalcogenides are promising candidates for ultrathin light modulators due to their highly tunable excitonic resonances at visible and near-infrared wavelengths. At cryogenic temperatures, large excitonic reflectivity in monolayer molybdenum diselenide (MoSe) has been shown, but the permittivity and index modulation have not been studied. Here, we demonstrate large gate-tunability of complex refractive index in monolayer MoSe by Fermi level modulation and study the doping dependence of the A and B excitonic resonances for temperatures between 4 and 150 K.

Colloidal HgTe Quantum Dot/Graphene Phototransistor with a Spectral Sensitivity Beyond 3 µm.

Infrared light detection enables diverse technologies ranging from night vision to gas analysis. Emerging technologies such as low-cost cameras for self-driving cars require highly sensitive, low-cost photodetector cameras with spectral sensitivities up to wavelengths of 10 µm. For this purpose, colloidal quantum dot (QD) graphene phototransistors offer a viable alternative to traditional technologies owing to inexpensive synthesis and processing of QDs.

Temperature-Dependent Charge Carrier Transfer in Colloidal Quantum Dot/Graphene Infrared Photodetectors.

Colloidal PbS quantum dot (QD)/graphene hybrid photodetectors are emerging QD technologies for affordable infrared light detectors. By interfacing the QDs with graphene, the photosignal of these detectors is amplified, leading to high responsivity values. While these detectors have been mainly operated at room temperature, low-temperature operation is required for extending their spectral sensitivity beyond a wavelength of 3 μm.

A Plasmonic Painter's Method of Color Mixing for a Continuous Red-Green-Blue Palette.

The ability of mixing colors with remarkable results had long been exclusive to the talents of master painters. By finely combining colors in different amounts on the palette, intuitively, they obtain smooth gradients with any given color. Creating such smooth color variations through scattering by the structural patterning of a surface, as opposed to color pigments, has long remained a challenge.

Nanoprinting organic molecules at the quantum level.

Organic compounds present a powerful platform for nanotechnological applications. In particular, molecules suitable for optical functionalities such as single photon generation and energy transfer have great promise for complex nanophotonic circuitry due to their large variety of spectral properties, efficient absorption and emission, and ease of synthesis. Optimal integration, however, calls for control over position and orientation of individual molecules.

Metasurfaces Leveraging Solar Energy for Icephobicity.

Inhibiting ice accumulation on surfaces is an energy-intensive task and is of significant importance in nature and technology where it has found applications in windshields, automobiles, aviation, renewable energy generation, and infrastructure. Existing methods rely on on-site electrical heat generation, chemicals, or mechanical removal, with drawbacks ranging from financial costs to disruptive technical interventions and environmental incompatibility. Here we focus on applications where surface transparency is desirable and propose metasurfaces with embedded plasmonically enhanced light absorption heating, using ultrathin hybrid metal-dielectric coatings, as a passive, viable approach for de-icing and anti-icing, in which the sole heat source is renewable solar energy.