All-optical diode based on asymmetric nonlinear optical absorption in ternary transition metal chalcogenides.

As the typical representative of ternary transition metal chalcogenides, CrPS and MnPS exhibit unique light-matter interactions, demonstrating great potential in photonic devices. In this work, we systematically studied the nonlinear optical (NLO) responses of CrPS and MnPS flakes by the I-scan technique. CrPS and MnPS flakes show saturable absorption and reverse saturation absorption excited by fs laser at wavelengths of 600 nm, respectively.

Development of a Zeolitic Imidazolate Framework Based Superhydrophobic Surface with Abrasion Resistance, Corrosion Protection, and Anti-icing.

Herein, a superhydrophobic surface was designed and fabricated based on the "lotus effect" construction mechanism. The zeolitic imidazolate framework (ZIF-90) micro-nanoparticles were initially synthesized via a one-pot method, combined with long-chain stearic acid (STA), and subsequently embedded in polyvinyl butyral (PVB) to form a superhydrophobic surface at room temperature. The superhydrophobic surface demonstrated mechanical stability and retained its superhydrophobicity with a water contact angle (CA) greater than 150°, even at a wear distance of 400 cm.

Revealing a Nonlinear Photocurrent in the Graphene/MoS Heterostructure via Terahertz Emission Spectroscopy.

Heterostructures composed of graphene (Gr) and transition metal dichalcogenides (TMDs) establish a new platform for optoelectronic applications. A substantial amount of research has concentrated on the interfacial charge transfer (CT) within heterostructures, yet investigations into the nonlinear effects occurring within these heterostructures have been relatively scarce. Utilizing terahertz (THz) emission spectroscopy, we demonstrate the synergistic interaction between interfacial CT and nonlinear photocurrent within the Gr/MoS heterostructure.

Anisotropic nonlinear optical responses of TaNiS flake towards ultrafast logic gates and secure all-optical information transmission.

Optical logic gates based on nonlinear optical property of material with ultrafast response speed and excellent computational processing power can break the performance bottleneck of electronic transistors. As one of the layered 2D materials, TaNiS exhibits high anisotropic mobility, exotic electrical response, and intriguing optical properties. Due to the low-symmetrical crystal structures, it possesses in-plane anisotropic physical properties.

Highly intrinsic carrier mobility in tin diselenide crystal accessed with ultrafast terahertz spectroscopy.

Tin diselenide (SnSe), a layered transition metal dichalcogenide (TMDC), stands out among other TMDCs for its extraordinary photoactive ability and low thermal conductivity. Consequently, it has stimulated many influential researches on photodetectors, ultrafast pulse shaping, thermoelectric devices, etc. However, the carrier mobility in SnSe, as determined experimentally, remains limited to tens of cmVs.

Charge Transfer in Graphene-MoS Vertical Heterostructures Tuned by Stacking Order and Substrate-Introduced Electric Field.

Vertical van der Waals heterostructures composed of graphene (Gr) and transition metal dichalcogenides (TMDs) have created a fascinating platform for exploring optical and electronic properties in the two-dimensional limit. Numerous studies have focused on Gr/TMDs heterostructures to elucidate the underlying mechanisms of charge-energy transfer, quasiparticle formation, and relaxation following optical excitation. Nevertheless, a comprehensive understanding of interfacial charge separation and subsequent dynamics in graphene-based heterostructures remains elusive.

Terahertz Biosensor Engineering Based on Quasi-BIC Metasurface with Ultrasensitive Detection.

Terahertz (THz) sensors have attracted great attention in the biological field due to their nondestructive and contact-free biochemical samples. Recently, the concept of a quasi-bound state in the continuum (QBIC) has gained significant attention in designing biosensors with ultrahigh sensitivity. QBIC-based metasurfaces (MSs) achieve excellent performance in various applications, including sensing, optical switching, and laser, providing a reliable platform for biomaterial sensors with terahertz radiation.

Persistent Charging of CsPbBr Perovskite Nanocrystals Confined in Glass Matrix.

Manipulation of persistent charges in semiconductor nanostructure is the key point to obtain quantum bits towards the application of quantum memory and information devices. However, realizing persistent charge storage in semiconductor nano-systems is still very challenge due to the disturbance from crystal defects and environment conditions. Herein, the two-photon persistent charging induced long-lasting afterglow and charged exciton formation are observed in CsPbBr perovskite nanocrystals (NCs) confined in glass host with effective lifetime surpassing one second, where the glass inclosure provides effective protection.

Tunable multifunctional polarization conversion in bilayer chiral metamaterials.

A chiral metamaterial composed of bilayer twisted split-ring resonators is proposed and demonstrated to realize tunable, dual-directional, and multifunctional polarization conversion for terahertz waves. Simulations show that the converter can selectively achieve linear-to-linear, linear-to-right-handed circular, or linear-to-left-handed circular polarization conversion by tuning the polarization and propagating direction of the incident waves. Stokes parameters, ellipticity, and a polarization rotation angle are introduced to determine the output polarization.

Anomalous Nernst Effect Induced Terahertz Emission in a Single Ferromagnetic Film.

Despite its important role in understanding ultrafast spin dynamics and revealing novel spin/orbit effects, the mechanism of the terahertz (THz) emission from a single ferromagnetic nanofilm upon a femtosecond laser pump still remains elusive. Recent experiments have shown exotic symmetry, which is not expected from the routinely adopted mechanism of ultrafast demagnetization. Here, by developing a bidirectional pump-THz emission spectroscopy and associated symmetry analysis method, we set a benchmark for the experimental distinction of the THz emission induced by various mechanisms.

Correction to "Terahertz Magnon-Polaritons in TmFeO".

[This corrects the article DOI: 10.1021/acsphotonics.7b01402.

Ultrafast Photocarrier Dynamics in Vertically Aligned SnS Nanoflakes Probing with Transient Terahertz Spectroscopy.

By employing optical pump Terahertz (THz) probe spectroscopy, ultrafast photocarrier dynamics of a two-dimensional (2D) semiconductor, SnS nanoflake film, has been investigated systematically at room temperature. The dynamics of photoexcitation is strongly related to the density of edge sites and defects in the SnS nanoflakes, which is controllable by adjusting the height of vertically aligned SnS during chemical vapor deposition growth. After photoexcitation at 400 nm, the transient THz photoconductivity response of the films can be well fitted with bi-exponential decay function.

Lattice-induced strong coupling in symmetric and asymmetric split-ring metamaterial arrays.

The intrinsic link between surface plasmon modes (eigenmodes) and lattice modes in subwavelength periodic structures is investigated based on the split-ring metamaterial structure. The paper shows that the strong coupling between the eigenmodes and the lattice modes can be achieved by appropriately adjusting the period of the metamaterial structure, and the emergence of new, to the best of our knowledge, modes at low frequencies is observed, resulting in a lower spectral loss of a single hybrid resonance and an increase in its factor up to 110. In addition, an asymmetric double-split-ring structure is proposed, and the Fano resonance is excited, giving rise to a spectral line with three resonance valleys.

Dynamical Response of Nonlinear Optical Anisotropy in a Tin Sulfide Crystal under Ultrafast Photoexcitation.

Analogous to black phosphorus, SnS processes folded structure that shows a strongly anisotropic optical absorption. Herein, by using ultrafast two-color pump and probe spectroscopy, the azimuthal angle dependence of nonlinear optical anisotropy in SnS is investigated. After 390 nm photoexcitation, the reflectivity of the 780 nm probe beam is first reduced significantly, followed by a complex alternation with the rotation of the sample along the -axis.

Photoinduced large polaron transport and dynamics in organic-inorganic hybrid lead halide perovskite with terahertz probes.

Organic-inorganic hybrid metal halide perovskites (MHPs) have attracted tremendous attention for optoelectronic applications. The long photocarrier lifetime and moderate carrier mobility have been proposed as results of the large polaron formation in MHPs. However, it is challenging to measure the effective mass and carrier scattering parameters of the photogenerated large polarons in the ultrafast carrier recombination dynamics.

Observation of Ultrafast Interfacial Exciton Formation and Relaxation in Graphene/MoS Heterostructure.

Heterostructures constructed from graphene and transition metal dichalcogenides (TMDs) have established a new platform for optoelectronic applications. After a large number of studies, one intriguing debate is the existence of the interfacial exciton in graphene/TMDs. Hereby, by combined optical pump-terahertz probe spectroscopy and transient absorption spectroscopy, we report the observation of the interfacial exciton in graphene/MoS heterostructure.

A Nomogram Model for Evaluating the Risk of Lymph Node Metastasis in cT2-cT4N0M0 Gastric Cancer Population.

BACKGROUND Neoadjuvant chemotherapy is an important treatment for advanced gastric cancer, but it has been unclear whether neoadjuvant chemotherapy is closely related to lymph node metastasis. Therefore, based on the disease characteristics of the cT2-cT4N0M0 gastric cancer population, this study established a nomogram prediction model of lymph node metastasis risk in this gastric cancer population to help clinicians optimize clinical decision-making. MATERIAL AND METHODS We analyzed the data of 336 patients with advanced gastric cancer with CT imaging stage of cT2-cT4N0M0 admitted to the Third Department of the Fourth Hospital of Hebei Medical University from 2015 to 2021.

Ultrafast Dynamics of Defect-Assisted Auger Process in PdSe Films: Synergistic Interaction between Defect Trapping and Auger Effect.

By using optical pump and terahertz probe spectroscopy, we have investigated the photocarrier dynamics in PdSe films with different thicknesses. The experimental results reveal that the photocarrier relaxation consists of two components: a fast component of 2.5 ps that shows the layer-thickness independence and a slow component that has typical lifetime of 7.

Ultrasensitive, light-induced reversible multidimensional biosensing using THz metasurfaces hybridized with patterned graphene and perovskite.

Biosensors based on terahertz (THz) metasurfaces have recently attracted widespread attention. However, few have been reported so far because it is a challenge to achieve ultrasensitive multidimensional detection in the THz spectrum. Here, we propose a novel THz biosensor that consists of a metasurfaces and a metal oxide semiconductor-like structure (MOSLS), which is based on patterned graphene-polyimide-perovskite.

Observation of Negative Terahertz Photoconductivity in Large Area Type-II Dirac Semimetal PtTe_{2}.

As a newly emergent type-II Dirac semimetal, platinum telluride (PtTe_{2}) stands out from other two dimensional noble-transition-metal dichalcogenides for the unique band structure and novel physical properties, and has been studied extensively. However, the ultrafast response of low energy quasiparticle excitation in terahertz frequency remains nearly unexplored yet. Herein, we employ optical pump-terahertz probe (OPTP) spectroscopy to systematically study the photocarrier dynamics of PtTe_{2} thin films with varying pump fluence, temperature, and film thickness.

Optically controlled ultrafast terahertz switching in wafer scale PtSe thin films.

In this study, we have reported a newly ultrafast optically modulated terahertz (THz) switch based on the transition metal dichalcogenide (TMD) material platinum diselenide (${{\rm PtSe}_2}$) with different thicknesses. The high-quality ${{\rm PtSe}_2}$ thin films with centimeter scale are fabricated on sapphire substrate by the chemical vapor deposition method. The optical pump and THz probe (OPTP) spectroscopy reveals that the THz response of the thin films is as fast as ${\sim} 2.

Ultrastrong magnon-magnon coupling dominated by antiresonant interactions.

Exotic quantum vacuum phenomena are predicted in cavity quantum electrodynamics systems with ultrastrong light-matter interactions. Their ground states are predicted to be vacuum squeezed states with suppressed quantum fluctuations owing to antiresonant terms in the Hamiltonian. However, such predictions have not been realized because antiresonant interactions are typically negligible compared to resonant interactions in light-matter systems.

Influence of doping for InSb on ultrafast carrier dynamics measured by time-resolved terahertz spectroscopy.

The influence of doping on the ultrafast carrier dynamics in InSb has been studied by time-resolved terahertz spectroscopy with photogenerated carrier densities from 1.5×10 to 9.5×10 at 800 nm.

Dynamic Modeling of Weld Bead Geometry Features in Thick Plate GMAW Based on Machine Vision and Learning.

Weld bead geometry features (WBGFs) such as the bead width, height, area, and center of gravity are the common factors for weighing welding quality control. The effective modeling of these WBGFs contributes to implementing timely decision making of welding process parameters to improve welding quality and enhance automatic levels. In this work, a dynamic modeling method of WBGFs is presented based on machine vision and learning in multipass gas metal arc welding (GMAW) with typical joints.

Magnetic field tuning of spin resonance in TmFeO single crystal probed with THz transient.

TmFeO, a canted antiferromagnet, has two intrinsic spin resonance modes in the terahertz (THz) frequency regime: quasi-ferromagnetic (q-FM) mode and quasi-antiferromagnetic (q-AFM) mode. Both the q-FM and q-AFM modes show strong magnetic field and temperature dependence. Hereby, by employing THz time-domain spectroscopy combined with external magnetic field and low temperature system, we systematically investigated the magnetic field induced frequency shift of q-FM and q-AFM modes as well as the temperature driven spin reorientation phase transition in TmFeO single crystal.