21 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 invention discloses a liquid gate graphene transistor sensor for rapidly detecting a cell factor IFN-gamma, and a preparation method and application thereof. The sensor adopts an IFN-gamma aptamer to modify a gate on a liquid gate graphene field effect transistor (SSGT); during detection, after the aptamer on the grid captures an IFN-gamma target substance, the configuration is changed, the charge is changed, and then the Dirac point of a transfer curve is shifted, so that the target substance is detected respectively, and detection of IFN-gamma is finally realized by establishing a concentration model of a target system. According to the invention, the disadvantages of complex flow, insufficient adaptability in a multi-sample environment, lack of real-time monitoring capability and the like of the traditional detection means are solved, the rapid detection of one or more cytokines in blood can be realized through the combination and disassembly of the grids, the rapid detection method can be used for cell experiment detection and animal experiment detection, and the rapid detection method has a certain practical value.

Provided in the present invention are an electromagnetic wave unidirectional cloaking apparatus and a preparation method, relating to the technical field of electromagnetic wave cloaking. The apparatus comprises a type I photonic crystal doped with loss impurities, a type II photonic crystal containing a cloaking substance, and a type I photonic crystal doped with gain impurities; the type I photonic crystal doped with loss impurities, the type II photonic crystal containing a cloaking susbtance, and the type I photonic crystal doped with gain impurities are arranged in sequence; the type I photonic crystals have Dirac-like dispersion and the type II photonic crystal has a photonic band gap, and the Dirac-like point frequency of the type I photonic crystal is the same as the band edge frequency of the photonic band gap of the type II photonic crystal; the loss impurities doped into the type I photonic crystal and the gain impurities doped into the type I photonic crystal satisfy the following conditions: the relative dielectric constants thereof satisfy complex conjugation, and the relative magnetic permeability thereof is 1. The cloaking effect of the apparatus of the present invention is unidirectional, and the cloaking electromagnetic wave frequency is tunable.

The invention provides a liquid gate graphene transistor antibiotic sensor for realizing real-time detection of bleomycin. According to the method, a probe ssDNA is fixed on the surface of a gate electrode of a graphene transistor through an Au-S bond. Wherein coexistence of Fe (II) and bleomycin can cause formation of a binary compound BLMFe (II), oxygen can be reduced into free radicals at recognition sites, and DNA degradation capacity is achieved. A BLMFe (II) complex is added into an electrolyte, ssDNA and BLMFe (II) react at a recognition site, so that part of ssDNA fragments fall off from the surface of a gate electrode, the double-electrode-layer interface characteristic between a transistor and a sample solution is changed, and Dirac point voltage and current in a graphene channel are changed. According to the graphene transistor antibiotic sensor provided by the invention, the drain voltage is fixed, the grid potential is changed, the lowest detection limit of bleomycin can reach 10 <-18 > M, bleomycin solutions with different concentrations are added, the current of the sensor is changed immediately, and the graphene transistor antibiotic sensor has very high sensitivity.

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 present invention discloses a dual-functional five-mode metamaterial structure with water-like and topological transmission characteristics, including a lattice unit. The lattice unit includes six metal arms, and an additional counterweight is provided on each of the six metal arms, with a total of six additional counterweights. The six additional counterweights are all in the shape of equilateral triangles, and are respectively four first additional counterweights, one second additional counterweight, and one third additional counterweight. The side length of the first additional counterweight is w, the side length of the second additional counterweight is w - dh, and the side length of the third additional counterweight is w + dh, where dh represents a set constant. By introducing structural perturbations in the PM, the present invention can open the Dirac point degeneracy at the K point to generate topological band inversion. By calculating the projected band structure of a supercell composed of two PMs with different topological valley phases, topological edge states are obtained, which have good robustness to defects such as bending and cavities.

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 invention discloses a dual-band multimode multiplexing two-dimensional photonic crystal cavity, a design method and an optical device. The dual-band multimode multiplexing two-dimensional photonic crystal cavity comprises at least one photonic crystal layer, the photonic crystal layer comprises a plurality of photonic crystal supercells, and the plurality of photonic crystal supercells form a two-dimensional topological structure; the energy band of the photonic crystal supercell has band gaps at two Dirac points, and the structural phase of the two-dimensional photonic crystal cavity is a non-zero integer multiple of 2 pi, so that the two-dimensional photonic crystal cavity has a plurality of light field modes.

The present invention relates to a full van der Waals spin terahertz emitter and a method for regulating the intensity and polarity of terahertz waves. The full van der Waals spin terahertz emitter includes: a femtosecond laser, a nanometer thin film, and a voltage source; the femtosecond laser is used to output pump laser that penetrates the nanometer thin film to generate a first terahertz pulse; the nanometer thin film is a full van der Waals heterostructure constructed by a non-ferromagnetic layer and a ferromagnetic layer; the material of the ferromagnetic layer is a two-dimensional magnetic material; the voltage source is used to input current to the non-ferromagnetic layer, regulate the position of the Fermi level of the non-ferromagnetic layer material from the Dirac point to change the intensity of the first terahertz pulse, and generate a second terahertz pulse with the opposite polarity. The present invention also provides a method for regulating the intensity and polarity of terahertz waves. The above terahertz wave generator uses a two-dimensional ferromagnetic material to prepare the ferromagnetic layer and constructs a full van der Waals heterostructure with a non-ferromagnetic layer made of a van der Waals topological material.

The invention provides a lead ion sensor based on a composite liquid gate transistor as well as a preparation method and application of the lead ion sensor, and belongs to the technical field of biosensors. The transistor lead ion sensor comprises a substrate, a source electrode, a drain electrode and a grid electrode, wherein the source electrode and the drain electrode are arranged on the substrate. A glassy carbon electrode is used as a grid electrode, the surface of the glassy carbon electrode is modified with a layer of nitrogen-doped graphene to serve as a base, gold nanoparticles are introduced to widen the conductivity of the glassy carbon electrode, meanwhile, the surface of a substrate material is modified with probe glutathione, the probe glutathione can be complexed with lead ions in a solution, and then the double-electric-layer characteristic between a transistor and a sample solution is changed; by measuring the Dirac point change of the device, the purpose of quantitative analysis is achieved. According to the lead ion concentration detection method, along with the change of the concentration of the target object, the lowest detection limit can reach 10 <-11 > M, the lowest response time reaches 100 s, and the sensor has high sensitivity, selectivity and stability.

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 unidirectional electromagnetic wave stealth device and a manufacturing method thereof. The device includes a first photonic crystal doped with a lossy dopant, a second photonic crystal containing an object to be cloaked and a first photonic crystal doped with a gain dopant, which are sequentially arranged. The first photonic crystal exhibits Dirac-like cone dispersion, the second photonic crystal has a photonic band gap, and a Dirac-like point frequency of the first photonic crystal is the same as a band-edge frequency of the photonic band gap of the second photonic crystal. The lossy dopant and the gain dopant are such that relative permittivities of the lossy dopant and the gain dopant are complex conjugates, and relative permeabilities of the lossy dopant and the gain dopant are 1. The stealth effect of the device is unidirectional, and the frequency of the cloaking electromagnetic wave is tunable.

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 discloses a method for constructing a Dirac point in an energy band of a photonic crystal. The method is based on energy band regulation of the photonic crystal, and a dielectric column is inserted into the photonic crystal structure to control the relative distance between energy bands, so that the Dirac point is constructed at a fixed position of the photonic crystal. The photonic crystal containing the Dirac point in the energy band has almost no spatial symmetry, and the application scenarios and application range of the photonic crystal Dirac point are greatly expanded.

The invention provides a transistor sensor for detecting pancreatic cancer markers and a preparation method thereof. A trace amount of miRNA-196a in the solution can be detected by detecting the current change in the channel; through a synergistic anti-pollution design, bovine serum albumin (BSA) is used as a blocking agent, polyadenine (polyAn) forms a hydrophilic layer, and the bovine serum albumin (BSA) and the polyadenine (polyAn) complement each other and have a synergistic effect, so that non-specific adsorption of polluting biomolecules is avoided. The graphene transistor biosensor provided by the invention can be used for detecting an extremely trace amount of miRNA-196a with the concentration as low as 10 <-18 > M, the response time is about 18 minutes, and the R2 value of a fitting straight line is 0.998; and obvious and correct Dirac point voltage change signals exist in a complex plasma environment. Compared with the prior art, the technical scheme provided by the invention not only maintains the advantages of high sensitivity, good specificity and the like of the graphene transistor sensor, but also endows the sensor with the performance of resisting nonspecific adsorption of biomolecules due to the introduction of the anti-pollution material.

The invention relates to the technical field of thermoelectric materials, in particular to a transverse thermoelectric material and a preparation method and application thereof, the transverse thermoelectric material is transition metal doped Mg3Bi2, the transition metal doped Mg3Bi2 is marked as Mg3Bi2: Mx, and M is a transition metal element; x ranges from 0 to 0.3 and is not equal to 0. Negative chemical pressure can be introduced into the Mg3Bi2 material by doping different transition metals, and the existence of the negative chemical pressure can promote an energy band structure to be converted from a topological insulator to topological semimetal and induce Dirac points with obvious linear dispersion characteristics, so that the electron mobility, the magnetic resistance and the transverse thermoelectric force of the material are greatly improved. The transverse thermoelectric material has a topological transformation structure from a topological insulator to Dirac semimetal, so that the transverse thermoelectric material has high transverse thermoelectric performance, and conversion between heat energy and electric energy is expected to be efficiently realized. Moreover, the preparation method of the transverse thermoelectric material is simple and easy to implement, large-scale preparation is easy, the production cost is reduced, and the production efficiency is improved.

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.