Tunable transmissive terahertz polarization rotator based on a resonance-decoupled metal-VO hybrid metasurface.

The emergence of novel tunable materials such as vanadium dioxide (VO), graphene, and black phosphorus has endowed terahertz (THz) metasurfaces with more flexibility and dynamic tunability, promoting the development of THz lasers, modulators, and detectors. In previous studies, most transmissive THz linear polarization rotators based on these materials are complicated in structure or suffer from poor performance, such as low transmittance and modulation depth. In this paper, we present a tunable transmissive THz linear polarization rotator based on VO.

Light funneling into localized acoustic graphene plasmons for extreme infrared and terahertz field enhancement and confinement.

Enhancing light-matter interaction through deep subwavelength-scale confinement is crucial for numerous applications like molecular sensing, optoelectronic devices, and non-linear optics. Here, we report the excitation of localized acoustic graphene plasmons (LAGPs) confined in a sub-micro- wide, nanometer-thick layer using a metal slit antenna. This approach enables light funneling in the infrared and terahertz regimes, leading to strong field enhancement and confinement.

Tailoring Infrared Light-Molecule Coupling for Highly Sensitive Cortisol Detection Employing Aptamer-Conjugated Gold Nanonails.

Chemically synthesized gold nanoantennas possess easy processability, low cost, and suitability for large-area fabrication, making them advantageous for surface-enhanced infrared (SEIRA) biosensing. Nevertheless, current gold nanoantennas face challenges with limited enhancement of biomolecular signals that hinder their practical applications. Here, we demonstrate that the coupling rate between antennas and molecules critically impacts the enhancement of molecular signals based on temporal coupled mode theory.

Polarity-Tunable Field Effect Phototransistors.

Field-effect phototransistors feature gate voltage modulation, allowing dynamic performance control and significant signal amplification. A field-effect phototransistor can be designed to be inherently either unipolar or ambipolar in its response. However, conventionally, once a field-effect phototransistor has been fabricated, its polarity cannot be changed.

Miniaturized infrared spectrometer based on the tunable graphene plasmonic filter.

Miniaturization of a conventional spectrometer is challenging because of the tradeoffs of size, cost, signal-to-noise ratio, and spectral resolution, etc. Here, a new type of miniaturized infrared spectrometer based on the integration of tunable graphene plasmonic filters and infrared detectors is proposed. The transmittance spectrum of a graphene plasmonic filter can be tuned by varying the Fermi energy of the graphene, allowing light incident on the graphene plasmonic filter to be dynamically modulated in a way that encodes its spectral information in the receiving infrared detector.

Ultrahigh Photogain Short-Wave Infrared Detectors Enabled by Integrating Graphene and Hyperdoped Silicon.

Highly sensitive short-wave infrared (SWIR) detectors, compatible with the silicon-based complementary metal oxide semiconductor (CMOS) process, are regarded as the key enabling components in the miniaturized system for weak signal detection. To date, the high photogain devices are greatly limited by a large bias voltage, low-temperature refrigeration, narrow response band, and complex fabrication processes. Here, we demonstrate high photogain detectors working in the SWIR region at room temperature, which use graphene for charge transport and Te-hyperdoped silicon (Te-Si) for infrared absorption.

Interface Engineering of a Silicon/Graphene Heterojunction Photodetector via a Diamond-Like Carbon Interlayer.

Silicon/graphene nanowalls (Si/GNWs) heterojunctions with excellent integrability and sensitivity show an increasing potential in optoelectronic devices. However, the performance is greatly limited by inferior interfacial adhesion and week electronic transport caused by the horizontal buffer layer. Herein, a diamond-like carbon (DLC) interlayer is first introduced to construct Si/DLC/GNWs heterojunctions, which can significantly change the growth behavior of the GNWs film, avoiding the formation of horizontal buffer layers.

Anomalous redshift of graphene absorption induced by plasmon-cavity competition.

Anomalous redshift of the absorption peak of graphene in the cavity system is numerically and experimentally demonstrated. It is observed that the absorption peak exhibits a redshift as the Fermi level of graphene increases, which is contrary to the ordinary trend of graphene plasmons. The influencing factors, including the electron mobility of graphene, the cavity length, and the ribbon width, are comprehensively analyzed.

Batch production of uniform graphene films via controlling gas-phase dynamics in confined space.

Batch production of continuous and uniform graphene films is critical for the application of graphene. Chemical vapor deposition (CVD) has shown great promise for mass producing high-quality graphene films. However, the critical factors affected the uniformity of graphene films during the batch production need to be further studied.

Electrically tunable graphene metamaterial with strong broadband absorption.

The coupling system with dynamic manipulation characteristics is of great importance for the field of active plasmonics and tunable metamaterials. However, the traditional metal-based architectures suffer from a lack of electrical tunability. In this study, a metamaterial composed of perpendicular or parallel graphene-AlO-graphene stacks is proposed and demonstrated, which allows for the electric modulation of both graphene layers simultaneously.

Resolved Infrared Spectroscopy of Aqueous Molecules Employing Tunable Graphene Plasmons in an Otto Prism.

Real-time and detection of aqueous solution is essential for bioanalysis and chemical reactions. However, it is extremely challenging for infrared microscopic measurement because of the large background of water absorption. Here, we proposed a wideband-tunable graphene plasmonic infrared biosensor to detect biomolecules in an aqueous environment, employing attenuated total reflection in an Otto prism configuration and tightly confined plasmons in graphene nanoribbons.

Impact of the pitch angle on the spin Hall effect of light weak measurement.

The spin Hall effect of light (SHEL), as a photonic analogue of the spin Hall effect, has been widely studied for manipulating spin-polarized photons and precision metrology. In this work, a physical model is established to reveal the impact of the interface pitch angle on the SHEL accompanied by the Imbert-Fedorov angular shift simultaneously. Then, a modified weak measurement technique is proposed in this case to amplify the spin shift experimentally, and the results agree well with the theoretical prediction.

Low Voltage Graphene-Based Amplitude Modulator for High Efficiency Terahertz Modulation.

In this paper, a high-efficiency terahertz amplitude modulation device based on a field-effect transistor has been proposed. The polarization insensitive modulator is designed to achieve a maximum experimental modulation depth of about 53% within 5 V of gate voltages using monolayer graphene. Moreover, the manufacturing processes are inexpensive.

Enhancement of the Photoresponse of Monolayer MoS Photodetectors Induced by a Nanoparticle Grating.

Photodetectors based on two-dimensional (2D) materials such as monolayer MoS are attractive because they can be directly integrated into the current metal-oxide semiconductor (CMOS) structures. Unfortunately, such devices suffer from low responsivity due to low absorption by the monolayer MoS. Combining MoS with plasmonic nanostructures is an alternative solution for enhancing the absorption of the 2D semiconductor, and this can drastically increase the photoresponsivity of the corresponding photodetector.

High efficiency active wavefront manipulation of spin photonics based on a graphene metasurface.

Metasurfaces have been widely studied for manipulating light fields. In this work, a novel metasurface element is achieved with a high circular polarization amplitude conversion efficiency of 88.5% that creates an opposite phase shift ranging from -180° to 180° between incidence and reflection for different spin components.

Space-Confined Synthesis of Core-Shell BaTiO@Carbon Microspheres as a High-Performance Binary Dielectric System for Microwave Absorption.

Binary dielectric composites are viewed as a kind of promising candidate for conventional magnetic materials in the field of microwave absorption. Herein, we demonstrate the successful fabrication of core-shell BaTiO@carbon microspheres through a space-confined strategy. The electromagnetic properties of BaTiO@carbon microspheres can be easily tailored by manipulating the relative content of carbon shells.

Light Trapping in Conformal Graphene/Silicon Nanoholes for High-Performance Photodetectors.

Hybrid graphene/silicon heterojunctions have been widely utilized in photodetectors because of their unique characteristics of high sensitivity, fast response, and CMOS compatibility. However, the photoresponse is restricted by the high reflectance of planar silicon (up to 50%). Herein, an improved graphene/Si detector with excellent light absorption performance is proposed and demonstrated by directly growing graphene on the surface of silicon nanoholes (SiNHs).

Ultrasensitive Molecular Detection by Improving the Mode Energy of Graphene Plasmons for Surface Enhanced Infrared Absorption Spectroscopy.

Ultrasensitive detection of molecules by graphene plasmons based surface enhanced infrared absorption spectroscopy (SEIRAS) has attracted considerable research interest in recent years. However, SEIRAS still suffers from low enhancement. Herein, we investigated the crucial factors that determined the enhancement of graphene plasmons based SEIRAS.

A Polarization-Sensitive Multiband Plasmonic Hot Electron Photodetector Based on Conformal MoS₂.

We present an insulator-semiconductor-metal plasmonic hot-electron photodetector based on a grating structure that uses monolayer MoS₂ as a semiconductor. Within the MoS₂ bandgap wavelength, the choice of design can be used to increase the photocurrent via the enhanced electric field of surface plasmons. Beyond the bandgap, hot electrons generated by surface plasmons can contribute to the photocurrent, which overcomes the limitation of the semiconductor's bandgap.

Ultrathin Bimetal Color Filter Based on Plasmonic Nanostructure.

Plasmonic subtractive color filters through a nanostructured ultrathin Ag film have attracted intensive attention due to their good durability, high color tunability and high transmission. However, Ag film suffers from discontinuity when the thickness is below 15 nm, which limits the further increasement of transmission efficiency. Herein a bimetal ultrathin (~10 nm) subtractive color filter with one dimensional nanogratings was demonstrated and fabricated.

Graphene-assisted multilayer structure employing hybrid surface plasmon and magnetic plasmon for surface-enhanced vibrational spectroscopy.

A graphene-assisted vertical multilayer structure is proposed for high performance surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA) spectroscopies on a single substrate, employing simultaneous localized surface plasmon in the visible region and magnetic plasmon resonance in the mid-infrared region. Such multilayer structure consists of a monolayer graphene sandwiched between Ag nanoparticles (NPs) and a metal-insulator-metal (MIM) microstructure, which can be easily fabricated by a standard surface micromachining process. Benefiting from the large near field enhancement by the hybrid plasmons in both visible and mid-infrared regions, a high enhancement factor of up to 10 for SERS and 10 for SEIRA can be achieved.

Mode energy of graphene plasmons and its role in determining the local field magnitudes.

We theoretically study the mode energy of graphene plasmons and its fundamental role in determining the local field magnitudes. While neglecting the magnetic field energy of the mode, we derive a concise expression for the total mode energy, which is independent on the details of the mode field distributions and valid for both propagating and localized modes. We find that the mean square of the local electric fields of a graphene plasmonic mode scales linearly with the light absorption rate of the mode and the electron relaxation time of graphene.

Ultraflexible and High-Performance Multilayer Transparent Electrode Based on ZnO/Ag/CuSCN.

Driven by huge demand for flexible optoelectronic devices, high-performance flexible transparent electrodes are continuously sought. In this work, a flexible multilayer transparent electrode with the structure of ZnO/Ag/CuSCN (ZAC) is engineered, featuring inorganic solution-processed cuprous thiocyanate (CuSCN) as a hole-transport antireflection coating. The ZAC electrode exhibits an average transmittance of 94% (discounting the substrate) in the visible range, a sheet resistance ( R) of 9.