192 results about "Broadband absorption" patented technology

The present invention is directed to photostable sunscreen and/or artificial tanning compositions including quantum dot nanocrystals of a material selected from semiconductor nanocrystals, modified semiconductor nanocrystals, multicomponent semiconductor/semiconductor nanocrystals, and hybrid semiconductor/metal nanocrystals, the quantum dot nanocrystals having an absorption band gap occurring at wavelengths higher than 400 nm whereby the quantum dot nanocrystals have substantial broadband absorption properties of ultraviolet light at wavelengths across the range of both UV-A (320-400 nm) and UV-B (280-320 nm), and a dermatologically acceptable carrier for the quantum dot nanocrystals. The present invention is further directed to photostable sunscreen and/or artificial tanning compositions including a material selected from metallic nanocrystals, multicomponent metal/metal nanocrystals, and alloyed metal nanocrystals, the metallic material having a surface plasmon resonance occurring sufficiently into the visible or infrared spectral region whereby broad absorption features due to electronic transitions, the broad absorption features located at higher energies, provide substantial broadband absorption properties of ultraviolet light at wavelengths across the range of both UV-A (320-400 nm) and UV-B (280-320 nm), and a dermatologically acceptable carrier for the metallic material.

A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.

The invention discloses an optical modulation terahertz broadband wave absorber based on doped silicon. A three-layer structure comprises a silicon substrate layer, a metamaterial layer and an opticalpumping source, which are sequentially arranged from bottom to top; the silicon substrate layer and the metamaterial layer are both boron-doped p-type silicon materials; and the metamaterial layer iscomposed of a unit structure array. The unit structure arrays are periodically arranged on the silicon substrate layer in an xoy plane; terahertz waves are incident on the wave absorber; the opticalpumping source is coupled into the wave absorber and excites electromagnetic resonance to realize broadband absorption of terahertz waves; and the optical pumping source generates a pumping light beamwhich is directly incident on the silicon substrate layer and the metamaterial layer to change the carrier concentration of doped silicon and realize the modulation function of the wave absorber on the absorption frequency band and the absorption rate of the terahertz waves. The terahertz wave absorption device is simple in structure, single in material, easy to process, high in terahertz wave absorption rate and wide in absorption bandwidth, has a light modulation function, and can be widely applied to multiple fields of imaging, stealth, communication, terahertz detection and the like.

The invention provides a micro-bridge structure of a broadband high-absorption terahertz wave and a fabrication method thereof, which belong to the technical field of imaging of a terahertz detection array at a room temperature and are used for solving the problem of low responsivity under a wide frequency band of a terahertz detector. The micro-bridge structure comprises a metal absorption film at a top layer, a metamaterial pattern at an intermediate layer and a micro electro-mechanical system (MEMS) micro bridge at a bottom layer, wherein silicon nitride dielectric layers are arranged among the metal absorption film, the metamaterial pattern and the MEMS micro bridge in a pairwise manner at intervals; the metal absorption film is an impedance-matching nano-scale metal absorption film; and the metamaterial pattern and the MEMS micro bridge jointly form a metamaterial absorption structure. By the impedance-matching nano-scale metal absorption thin film, the broadband absorption of the terahertz wave can be achieved, and high absorption of the terahertz can be guaranteed through the metamaterial absorption structure jointly formed by the metamaterial pattern and the MEMS micro bridge; the performance for broadband spectrum response and high absorption of the terahertz wave is achieved, and the responsivity of a micro-bridge structurized detection unit to the terahertz wave is comprehensively improved.

The invention discloses a preparation method of a VO2 thin film composite structure for a near-infrared multi-band absorber. The composite structure mainly comprises a substrate sapphire, a gold reflection layer, a silicon dioxide nanosphere array and a vanadium dioxide film. The preparation method of the VO2 thin film composite structure for the near-infrared multi-band absorber is characterizedin that the gold film reflection layer is plated on a sapphire substrate through evaporation, the single-layer silicon dioxide sphere array is lifted on the gold film, a metal vanadium thin film is obtained through magnetron sputtering, and the vanadium dioxide film is prepared by a rapid thermal annealing method, so that the composite nanometer structure is formed, and near-infrared multi-broadband absorption is realized.

The invention discloses a method and a device for realizing wave absorbing of graphene at a visible light waveband, and belongs to the field of photoelectric detection and micro-nano optical, mechanical and electrical systems. A multi-groove structure provided by the invention is a periodic micro-structure, a primitive cell (a basic unit of the structure) of the periodic micro-structure is formedby a plurality of narrow metal grooves with the same width and different depths, a dielectric coating layer is filled into the grooves and above the grooves, and the graphene is deposited above the dielectric coating layer. For TM polar incident light waves, due to a cavity resonance effect of the grooves, the grooves with different depths correspond to different graphene light absorption wavelengths, and broadband absorption of the graphene at the visible light waveband can be realized through combination of the grooves with the different depths. In addition, an absorption spectrum of a waveabsorber is insensitive to the change of an incident angle, and even the incident angle is obviously changed, the graphene still has excellent broadband light absorption performance; and the method and the device have an application prospect in the fields such as light modulators, solar cells, touch screens, biological sensing and the like.

A graphene electro-optic modulation device based on a photonic crystal nanometer beam resonant cavity comprises a pair of electrodes, a graphene layer, an SOI substrate, an optical coupling waveguide, an PCNC and an N type silicon doping area, wherein the optical coupling waveguide, the PCNC and the N type silicon doping area are sequentially arranged on the SOI substrate in parallel, the graphene layer is arranged on the optical coupling waveguide, the PCNC and the N type silicon doping area, and the two electrodes are arranged at the portions, on the N type silicon doping area and the optical coupling waveguide, of the graphene layer respectively. The material advantages of broadband absorption of graphene, high mobility of carriers and the like and the structure advantages of small size and large FSR of the PCNC are integrated, the problem that in a current micro-ring resonant cavity graphene modulation device, FSR and size change in opposite ways is solved, the good modulation performance is achieved, and wide application prospects are achieved in optical fiber communication and optical interconnection systems.

The invention relates to a microwave absorber with broadband absorption characteristics, in particular to a broadband microwave absorber based on a folded dipole. According to the broadband microwave absorber, a folded dipole antenna serves as a design starting point, an antenna array with a broadband is designed based on a smith chart impedance adjustment method, furthermore, a feed source is replaced by a load resistor based on the reciprocity principle of the antenna, and therefore the microwave absorber with the broadband absorption characteristics is obtained. A dielectric layer of the absorber is of a double-layer structure, the upper layer is a common dielectric substrate, and the lower layer is common polystyrene foam materials (the dielectric constant is approximately 1.07). Although double-layer dielectric materials are adopted, a single-layer metal SMD circuit is adopted to be used in cooperation with a thin film SMD resistor. The broadband microwave absorber based on the folded dipole is simpler in structure, easier to process, low in cost and light in weight, and therefore mass production can be achieved.

The present invention relates to a method for manufacturing silicon thin-film solar cells, including: providing a substrate; forming a first electrode on the substrate; forming a first doped semiconductor layer on the first electrode by chemical vapor deposition; forming an intrinsic layer on the first doped semiconductor layer by chemical vapor deposition, where the intrinsic layer includes a plurality of amorphous/nanocrystalline silicon layers, and the intrinsic layer has various energy bandgaps formed by varying average grain sizes of the amorphous/nanocrystalline silicon layers; forming a second doped semiconductor layer on the intrinsic layer by chemical vapor deposition, where one of the first doped semiconductor layer and the second doped semiconductor layer is a p-type amorphous silicon layer and the other is an n-type amorphous/nano-microcrystalline silicon layer; and forming a second electrode on the second doped semiconductor layer. Accordingly, the present invention can achieve broadband absorption in a single junction structure.

The invention belongs to the field of electromagnetic wave absorption and radiation control, and in particular relates to a design method of a terahertz broadband absorbing metamaterial. According to the effective medium theory, and using CST microwave studio to obtain S parameters through frequency domain simulation, the periodic unit structure is at x Both the and y directions are periodically distributed, and are set as periodic boundary conditions. Combining the parameters S11 and S21 obtained by scanning, the impedance value is calculated. By changing the period of the unit structure and the size of the metal thin film and dielectric material, the corresponding absorption frequency is adjusted, and multiple metal thin films and dielectric materials are cross-stacked in one unit period, so that the absorption lines corresponding to different resonant circular frustums are superimposed. The invention can effectively broaden the absorption spectrum of the terahertz frequency band, so that the frequency band with an absorption rate exceeding 90% can be widened, and meanwhile, a certain high relative absorption bandwidth can be guaranteed. And the first 9 absorption peaks are caused by the interior of the unit structure, so they are not affected by the period.

The invention discloses a broadband tunable terahertz absorber based on vanadium dioxide and a preparation method thereof. The broadband tunable terahertz absorber unit section area is a square, and the broadband tunable terahertz absorber is composed of a base layer, a composite structure layer, a dielectric layer and a metal structure layer in order form bottom to top. The composite structure layer is formed by the dielectric layer inlaying a phase change material square structure, and the metal structure layer is formed by nesting a metal square frame and a metal block. The resonance structure is adopted to perform spatial overlapping in the longitudinal direction to achieve the broadband absorption of the terahertz waves, and the electrical conductivity of the phase change material inthe composite structural layer can be changed by external excitation such as a temperature and the illumination, and the absorption efficiency of the terahertz waves is modulated.

The invention relates to manganese cerium doped nickel zinc ferrite nano wave absorbing powder and a preparation method of the manganese cerium doped nickel zinc ferrite nano wave absorbing powder. According to the manganese cerium doped nickel zinc ferrite nano wave absorbing powder, a proper amount of manganese and cerium are added into nickel zinc ferrite to prepare nano nickel-based ferrite, the widening and matching thickness of a wave absorbing frequency band is reduced, and the wave absorbing powder meets the requirements for high absorption and the wide frequency band. According to the chemometry general formula Mn0.2+2yNi0.5-yZn0.3-yCexFe2-xO4 of the wave absorbing powder, a sol-gel method is adopted, nickel zinc ferrite precursors with different manganese cerium doping amounts are obtained, and the manganese cerium doped nickel zinc ferrite nano wave absorbing powder is obtained after high-temperature calcination. The process is simple, energy consumption is reduced, the wave absorbing powder is good in electromagnetic performance, and broadband absorption on radar waves can be achieved within the frequency band of 2 GHz to 18 GHz.

The invention provides a graphene electro-optical modulator based on a high-Q-value annular resonant cavity. The graphene electro-optical modulator based on the high-Q-value annular resonant cavity comprises a high-Q-value annular resonant system. A part of the perimeter of an annular waveguide of the high-Q-value annular resonant system is adopted for covering and manufacturing a double-layer graphene thin film modulation system. The double-layer graphene thin film modulation system comprises a bottom layer dielectric layer, bottom layer graphene, a middle dielectric layer and top layer graphene. A voltage V(t) is added between the top layer graphene and the bottom layer graphene. According to the modulator, material advantages such as high broadband absorption and carrier mobility of graphene and the structure advantage of optical path amplification of the high-Q-value annular optical resonant cavity are integrated, the modulation depth is increased, the maximum modulation frequency is increased in the mode that RC delay is reduced through reduction of the area of the graphene, and therefore the problem that the modulation depth and the modulation bandwidth in an existing straight waveguide graphene modulator are decreased and increased alternately is solved. The 3dB bandwidth can reach the modulation frequency of over 100 GHz expectantly.

The invention discloses a visible light broadband absorption structure and a preparation method thereof. The structure is characterized by comprising a metal substrate layer and a nano-structure, wherein the metal substrate layer includes a first surface and a second surface arranged opposite to the first surface; the nano-structure is arranged on the first surface of the metal substrate layer and in an arrayed mode, and nano array units are formed; the nano-structure is made of metal material. The nano array units of the visible light broadband absorption structure are arranged on the metal substrate layer, the structure is simple, and preparation is easy; according to another optimal scheme, the metal substrate layer and the nano-structure are of an integral structure, so that the average absorption efficiency of the wave band in 400-600 nm is larger than 92%, and the absorption efficiency of the wave band in 420 nm and in 560 nm is close to 100%.

The invention discloses a broadband transparent wave-absorbing material based on a double-layer conductive film. The material comprises a three-layer transparent medium, and a transparent conductive film is arranged on one surface of two transparent medium plates. The resistance value of the conductive film and the wave absorbing structure are optimally designed, so that incident electromagnetic waves with a relatively wide frequency band are lost in a wave absorbing body. Via such structure, broadband absorption can be achieved, meanwhile, high visible light permeability is achieved, the double-layer resistive film is not provided with a common pattern structure, etching is not needed, and therefore the machinability of the broadband wave absorber is high. The material of the invention has the advantages that the unit structure is simple, the thickness is small, the absorption frequency band of the microwave band electromagnetic wave is wide, the transmittance of the microwave band electromagnetic wave is low, the transmittance of visible light is high, and the manufacturing cost is low.

The invention discloses a selective absorption emitter. The selective absorption emitter comprises a substrate, a metal film covering the substrate and a cell array arranged on the metal film, whereinthe unit array is composed of a plurality of basic units which are arranged at intervals and have the same shape and the same size, each basic unit is composed of a plurality of stacks which are sequentially stacked from top to bottom, each stack comprises a metal layer and a dielectric layer located on the lower side of the metal layer or two dielectric layers with different refractive indexes,and the included angle between the side surfaces of the basic units and the normal of the substrate is minus 80-80 degrees. The selective absorption emitter is a broadband absorption emitter with wavelength selectivity. The correlation degree between the working wavelength of the emitter and the diameter or the length of the tops and the bottoms of the basic units in the unit array is small, the requirement on the precision of preparation technology is low, when the working wavelength of the emitter ranges from 8 microns to 13 microns, and high absorption and high emissivity are achieved, theemitter can be used for passive radiation refrigeration, and the required absorption characteristics can be obtained in other wavelength ranges by changing array design parameters.

The invention relates to the technical field of electromagnetic functional materials, in particular to soft magnetic nanocrystalline metal or alloy sheet-shaped particles with internal grain orientation and a microwave absorbing material. The soft magnetic nanocrystalline metal or alloy sheet-shaped particles with the internal grain orientation are obtained by taking spherical or spheroidic soft magnetic metal or alloy particles with a certain grain size as a raw material and carrying out wet ball milling or stirring milling. According to the invention, grain orientation is introduced into soft magnetic nanocrystalline metal or alloy absorbent particles, and the obtained soft magnetic sheet-shaped particles have significantly improved magnetic loss, especially at the frequency of 4 GHz orbelow, and can be used as a high-quality microwave absorbent to effectively improve the low-frequency and broadband absorption performance of the wave-absorbing material.

The invention discloses Mn<4+> doped fluoride red light fluorescent powder for a high color rendering and warm white light LED (Light Emitting Diode) and a preparation method of the Mn<4+> doped fluoride red light fluorescent powder. The chemical composition of a fluorescent powder material is Rb2AF6:xMn<4+>, wherein A is Zr or Ti, x is the mol percentage coefficient of Mn<4+> doped ions relative to the A, and the x is greater than or equal to 1.25 percent and smaller than or equal to 20 percent. The fluorescent powder material has the effects of broadband absorption and narrowband emission, and can be used for packaging a high-quality LED. The preparation method comprises the following steps: at room temperature, adding K2MnF6 powder into water, and stirring until the power is completely dissolved; then adding RbF powder and H2AF6 aqueous solution, continuously stirring until the substances are dissolved, centrifuging, washing and drying to obtain an orange-yellow sediment, namely the Mn<4+> doped fluoride red light fluorescent powder for the high color rendering and warm white light LED. The preparation method disclosed by the invention has the advantages of simplicity and convenience in operation, greenness, environment friendliness, mild reaction conditions, high efficiency, quickness and suitability for industrial large-scale production.

The invention relates to the technical field of detectors, in particular to a strong-absorption optothermal detector and a preparation method thereof. The optothermal detector is constituted by a substrate layer, an optothermal detecting structure, a first electrode and a second electrode. The substrate layer is covered with the optothermal detecting structure, and the first electrode and the second electrode are connected to the two sides of the optothermal detector correspondingly. The optothermal detecting structure comprises a thermal-sensitive line, a plurality of micro holes are formed in the upper surface of the thermal-sensitive line, a noble metal particle layer adheres to each of the surface of the thermal-sensitive line and the surfaces of the inner walls of the micro holes to increase the acting area of incident light and the noble metal particle layers so as to increase absorption of the incident light, and thus stronger surface plasmon resonance is caused to form broadband absorption. The micro holes are made of thermal-sensitive materials, heat absorbed by the optothermal detecting structure is transmitted more advantageously, the detecting sensitivity is improved advantageously, the optothermal detecting precision is improved advantageously, and the application range is enlarged advantageously.

The invention relates to the technical field of wave absorbing materials, particularly to a carbon fiber/amorphous alloy composite electromagnetic wave absorbing material and a preparation method thereof. The carbon fiber/amorphous alloy composite electromagnetic wave absorbing material is prepared by compounding carbon fiber and Ni-Co-Fe-P amorphous alloy layers. The carbon fiber/amorphous alloycomposite electromagnetic wave absorbing material has electromagnetic loss characteristics effectively integrating resistance loss, dielectric loss and magnetic loss and meanwhile is a high-performance-intelligence electromagnetic wave absorbing material capable of achieving electromagnetic parameter adjustability and high-strength and broadband absorption.

The invention discloses a method for enhancing single-layer graphene broadband absorption based on a strong coupling effect, wherein a graphene nanometer strip array is selected as an absorption layer, a metallic channel array as a substrate; a corresponding filling medium is arranged in the metallic channel; graphene surface plasmon resonance is excited through the graphene nanometer strip array;excitation of a magnetic resonance mode is supported through the metallic channel so that hybrid fields generated by strong coupling between the two modes are concentrated at the graphene, finally realizing enhancement of a broadband absorption effect of the graphene, wherein the graphene nanometer strip array used only contacts with one edge of the metallic trapezoid channel array, thereby meeting the resonance condition that excitation of the strong coupling effect requires a relatively high-quality factor graphene plasmon mode. The enhanced absorption broadband in the invention is coveredat the mid-infrared band, has the features of high band pass, low fluctuation, high rate and the like, and can be applied to an integrated all-optical network.