10 results about "Dirac point" patented technology

This application relates to a monolithically integrated multi-wavelength topological cavity surface-emitting laser (PCSEL) array. According to one embodiment, a monolithically integrated PCSEL array includes multiple PCSELs formed from the same semiconductor layer, at least one layer of which is formed as a photonic crystal layer, or the laser also includes a separate photonic crystal layer. The photonic crystal layer includes multiple supercell structures, each with substructures having multiple independent one-dimensional parameters. At least two independent one-dimensional parameters of one or more substructures are modulated to be greater than or less than their equilibrium position to open the Dirac point of the supercell's bandgap at the equilibrium position. Around any point in the photonic crystal layer, the modulation of the two independent one-dimensional parameters of the supercell forms a vortex structure, which corresponds in parameter space to one or more turns around the equilibrium position. The supercell lattice constants of the two lasers can be different to emit lasers of different wavelengths.

The application discloses a method for realizing optical wave and terahertz near-zero refractive index based on a nonlinear mixed waveguide, and steps are as follows: thin film lithium niobate is selected as a nonlinear material to process a mixed waveguide; a one-dimensional corrugated waveguide is used on the mixed waveguide to show a Dirac point-like dispersion characteristic at a Gamma point; an average nonlinear coupling coefficient of the mixed waveguide is calculated, and the quality factor of the zero-refractive-index waveguide is optimized by adjusting the thickness and period of the thin film lithium niobate; hollow rectangular metal waveguides are arranged around the thin film lithium niobate waveguide, and are used for guiding the propagation of terahertz waves and enhancing the nonlinear interaction in the difference frequency process; and the near-zero refractive index of various terahertz frequencies is realized by changing the width of the hollow rectangular metal waveguide. By jointly designing the nonlinear mixed waveguide of the terahertz and optical wave near-zero refractive index, the problems of phase mismatch and weak nonlinear interaction of the conversion of the optical wave to the terahertz wave are solved, so that the efficient conversion of the optical wave to the terahertz wave across the wave band is realized through on-chip optical difference frequency.

The application provides a temperature-adjustable acoustic topological insulator. By adjusting the environmental temperature, the four-fold Dirac point degeneracy at the Gamma point can be opened, resulting in the band inversion between the two-fold degenerate dipole state and quadrupole state, and a topological phase transition is realized. The evolution law of the topological state with temperature is numerically studied, and a new type of topological acoustic switch is constructed. By controlling the topological phase through temperature, the non-contact active regulation of the interface state in the structure can be realized, and the switching effect is exhibited. The research of the application can provide a corresponding reference for the intelligent control of sound and vibration of acoustic topology.

The application discloses a two-dimensional Ta-S intrinsic topological superconducting material and an electronic structure regulation method thereof. The material is a two-dimensional monolayer crystal of TaS, Ta3S2 and Ta2S, a Dirac point and a Van Hove singularity exist simultaneously near a Fermi level, has intrinsic superconductivity, and has a superconducting transition temperature of 3.731 K-5.799 K; under the action of spin-orbit coupling, the material presents a Z2=1 nontrivial topological state and has a gapless topological edge state. The electronic structure is precisely regulated through components, stress, spin-orbit coupling and electroacoustic coupling. The material is single in composition, stable in structure and can be prepared experimentally, and is suitable for the fields of topological superconductivity and quantum devices.

The invention provides a preparation and detection method of a liquid gate graphene transistor sensor for uric acid detection. Zinc oxide quantum dots are modified on the surface of a gate electrode of the transistor, and uricase is fixed on the zinc oxide quantum dots. The zinc oxide quantum dots have a large specific surface area, can improve active sites of enzyme adsorption, improve the adsorption capacity of the enzyme and optimize the catalytic conditions of the enzyme; and the zinc oxide quantum dots have high electric points and can be electrostatically combined with uricase with negative electricity, so that the uricase can be fixed on the gold electrode. The sensor detects uric acid by detecting Dirac point voltage change and channel current change. The detection limit of the sensor reaches 10 <-18 > M, the detection range is 10 <-18 >-10 <-6 > M, and the content of uric acid in human saliva is measured. Clinical experiments prove that the uric acid level in saliva of a subject is highly related to the uric acid level in blood of the subject.

The invention provides a preparation method of a two-dimensional Moire photonic crystal single-mode cavity, which comprises the following steps: S1, acquiring two layers of photonic crystal templates with triangular lattices with the same parameters, overlapping the two layers of photonic crystal templates, selecting a C2 symmetry point to twist the two photonic crystal templates by a preset angle and twist the two photonic crystals to the same layer, the C2 symmetry point is the central point of a rhombus formed by four air holes in the central position of each photonic crystal, and the single-layer triangular lattice photonic crystal has a Dirac point at the high symmetry point K in the inverted space; s2, adjusting outward displacement of two pairs of air holes closest to a C2 symmetry point in the photonic crystals twisted to the same layer based on the gain medium to obtain a Moire photonic crystal single-mode cavity structure template comprising a plurality of Moire photonic crystal cavities; and S3, etching on a gain medium mask according to the moire photonic crystal single-mode cavity structure template in the step S2 by adopting a micro-nano processing technology to obtain a two-dimensional moire photonic crystal single-mode cavity.

The application belongs to but is not limited to the technical field of condensed matter physics and quantum functional devices, and discloses a two-dimensional topological superconducting device with negative magnetoresistance and spin Hall effect. The device is based on a single-layer In2O two-dimensional material to construct a device system. By utilizing the II-type Dirac point structure formed near the Fermi level of the material, and splitting into Weyl points with non-zero topological charge under the spin-orbit coupling effect, a nontrivial topological electronic structure is formed in the momentum space. The two-dimensional topological superconducting device proposed in the application theoretically realizes the unification of topological state, negative magnetoresistance, spin Hall effect and superconducting behavior in the same material system, avoids the shortcomings of relying on complex heterostructures or multi-material systems in the prior art, and has the advantages of simple structure, easy integration and synergistic regulation of multiple physical effects.

This application relates to topological resonators and devices including topological resonators. A topological resonator may include a three-dimensional photonic or phononic crystal having a plurality of supercells modulated at least three independent degrees of freedom to open three-dimensional Dirac points in its band structure, forming a band gap. The intensity parameters of the modulation at the three independent degrees of freedom form a three-dimensional parameter space around an origin. The origin in the three-dimensional parameter space corresponds to a region in real space where the intensity parameters of the modulation at the three independent degrees of freedom are zero, thus the supercell has an equilibrium region of the three-dimensional Dirac point. In real space, with the equilibrium region as the center, the modulation at the three independent degrees of freedom in each direction corresponds to traversing or covering a closed surface around the origin W times continuously or discretely in the three-dimensional parameter space, where W is any positive or negative integer and the absolute value of W corresponds to the number of topological modes of the topological resonator.

The invention provides a method for detecting a depression marker serotonin by using a liquid gate transistor sensor, which is characterized in that a DNA probe is selected as a DNA single-stranded sequence, the tail end of the probe is modified with sulfydryl, and the sulfydryl is fixed on the surface of a gold gate through an Au-S bond. The detection principle is that the serotonin is captured on the surface of the gold gate after being identified by the probe, and the probe generates conformational change after identifying the serotonin, so that the tail end with negative electricity extends towards the direction far away from the surface of the gold gate, and the potential change of the surface of the gate is caused; the Dirac point voltage of the transmission curve of the liquid gate graphene transistor moves towards the negative gate voltage direction, and the serotonin content can be detected by detecting the voltage change of the Dirac point of the transfer curve in the channel or the channel current change. A clinical sample is detected by the sensor, and the serotonin level of a depression patient is relatively high and is consistent with a clinical diagnosis result.

A two-dimensional topological photonic crystal cavity, a design method thereof and an application in a laser. The two-dimensional topological photonic crystal cavity comprises multiple photonic crystal supercells, the multiple photonic crystal supercells having vortex-shaped structural variation around a center of the two-dimensional topological photonic crystal cavity, and bands of the multiple photonic crystal supercells having Dirac points at balance positions of the vortex-shaped structural variation. The two-dimensional topological photonic crystal cavity, also called the Dirac vortex cavity, is characterized by having large mode field area, large free spectral range, narrow beam divergence angle, arbitrary mode degeneracy and compatibility with plurality of types of substrate material, and may be used in a surface-emitting semiconductor laser, enabling stable single-transverse-mode and single-longitudinal-mode operation, while ensuring broad-area and high-power output of a laser.