Control of Quantized Spontaneous Emission from Single GaAs Quantum Dots Embedded in Huygens' Metasurfaces.

Advancements in photonic quantum information systems (QIS) have driven the development of high-brightness, on-demand, and indistinguishable semiconductor epitaxial quantum dots (QDs) as single photon sources. Strain-free, monodisperse, and spatially sparse local-droplet-etched (LDE) QDs have recently been demonstrated as a superior alternative to traditional Stranski-Krastanov QDs. However, integration of LDE QDs into nanophotonic architectures with the ability to scale to many interacting QDs is yet to be demonstrated.

Continuous wave terahertz detection using 1550 nm pumped nonlinear photoconductive GaAs metasurfaces.

Terahertz (THz) continuous wave (CW) spectroscopy systems can offer extremely high spectral resolution over the THz band by photo-mixing high-performance telecommunications-band (1530-1565 nm) lasers. However, typical THz CW detectors in these systems use narrow band-gap photoconductors, which require elaborate material growth and generate relatively large detector noise. Here we demonstrate that two-step photon absorption in a nano-structured low-temperature grown GaAs (LT-GaAs) metasurface which enables switching of photoconductivity within approximately one picosecond.

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface.

The effect of terahertz (THz) pulse generation has revolutionized broadband coherent spectroscopy and imaging at THz frequencies. However, THz pulses typically lack spatial structure, whereas structured beams are becoming essential for advanced spectroscopy applications. Nonlinear optical metasurfaces with nanoscale THz emitters can provide a solution by defining the beam structure at the generation stage.

Correction to "Terahertz Pulse Generation from GaAs Metasurfaces".

[This corrects the article DOI: 10.1021/acsphotonics.1c01908.

Terahertz Pulse Generation from GaAs Metasurfaces.

Ultrafast optical excitation of select materials gives rise to the generation of broadband terahertz (THz) pulses. This effect has enabled the field of THz time-domain spectroscopy and led to the discovery of many physical mechanisms behind THz generation. However, only a few materials possess the required properties to generate THz radiation efficiently.

Ionically Connected Floating Electrodes for Long-Distance (>1 mm) Coplanar-Gating Graphene Transistors.

Exploiting the long-range polarizability of an electrolyte based on ion migration, electric double-layer transistors (EDLTs) can be constructed in an unconventional configuration; here, the gate electrode is placed coplanarly with the device channel. In this paper, we demonstrate the influence of the distance factors of the electrolyte layer on the operation of EDLTs with a coplanar gate. As the promptness of the electric double-layer formation depends on the distance between the channel and the gate, the dynamic characteristics of a remote-gated transistor degrade with long distances.

Polarization Selective Color Filter Based on Plasmonic Nanograting Embedded Etalon Structures.

In this paper, we propose a polarization-selective color filter that can generate two different color informations simultaneously depending on the polarization direction. The proposed color filter is mainly composed of the etalon structure to generate the color by the structural resonance properties while the upper layer of the etalon is made of plasmonic nanogratings to promote polarization-dependent color properties. When the duty ratio of the silver nanogratings is fixed, the proposed color filter can maintain identical optical properties for orthogonal polarization, while the etalon structure of the proposed color filter can manipulate different color information depending on the cavity height for the horizontal polarization.

Wireless-Powered Chemical Sensor by 2.4 GHz Wi-Fi Energy-Harvesting Metamaterial.

Metamaterial Sensors show significant potential for applications ranging from hazardous chemical detection to biochemical analysis with high-quality sensing properties. However, they require additional measurement systems to analyze the resonance spectrum in real time, making it difficult to use them as a compact and portable sensor system. Herein, we present a novel wireless-powered chemical sensing system by using energy-harvesting metamaterials at microwave frequencies.

Electrically Controllable Molecularization of Terahertz Meta-Atoms.

Active control of metamaterial properties is critical for advanced terahertz (THz) applications. However, the tunability of THz properties, such as the resonance frequency and phase of the wave, remains challenging. Here, a new device design is provided for extensively tuning the resonance properties of THz metamaterials.

Control over Electron-Phonon Interaction by Dirac Plasmon Engineering in the BiSe Topological Insulator.

Understanding the mutual interaction between electronic excitations and lattice vibrations is key for understanding electronic transport and optoelectronic phenomena. Dynamic manipulation of such interaction is elusive because it requires varying the material composition on the atomic level. In turn, recent studies on topological insulators (TIs) have revealed the coexistence of a strong phonon resonance and topologically protected Dirac plasmon, both in the terahertz (THz) frequency range.

Electromagnetic dipole coupling mechanism in layered terahertz metamaterials.

Interplay between adjacent dipoles is an experimental priori for designing artificially-engineered structure because the dipole coupling is one critical factor for determining the electromagnetic response in metamaterials. Although numerous investigations have been performed to study the coupling effect of the split-ring resonator (SRR), the interlayer dipole coupling of its complementary SRR, called C-SRR, has been largely unexplored. Here, we present experimental and theoretical investigations on the electromagnetic coupling effect in the two stacks of layered C-SRR structures.