958 results about "Quasi-crystals" patented technology

PCT No. PCT / GB97 / 00817 Sec. 371 Date Apr. 13, 1998 Sec. 102(e) Date Apr. 13, 1998 PCT Filed Mar. 24, 1997 PCT Pub. No. WO97 / 36198 PCT Pub. Date Oct. 2, 1997An optical diffraction grating is formed from a region of photonic crystalline material Light is coupled into the photonic crystalline material, and the grazingly emergent output beam is collected. The photonic crystalline material may include an array of holes formed in a substrate of dielectric material, e.g., InP, and integrated with planar waveguide structures.

The present invention provides methods for hermetically sealing luminescent nanocrystals, as well as compositions and containers comprising hermetically sealed luminescent nanocrystals. By hermetically sealing the luminescent nanocrystals, enhanced lifetime and luminescence can be achieved.

The present invention relates in general to coupling of light from one or more input waveguides to an output waveguide or output section of a waveguide having other physical dimensions and / or optical properties than the input waveguide or waveguides. The invention relates to an optical component in the form of a photonic crystal fibre for coupling light from one component / system with a given numerical aperture to another component / system with another numerical aperture. The invention further relates to methods of producing the optical component, and articles comprising the optical component, and to the use of the optical component. The invention further relates to an optical component comprising a bundle of input fibres that are tapered and fused together to form an input coupler e.g. for coupling light from several light sources into a single waveguide. The invention still further relates to the control of the spatial extension of a guided mode (e.g. a mode-field diameter) of an optical beam in an optical fibre. The invention relates to a tapered longitudinally extending optical waveguide having a relatively larger cross section that over a certain longitudinal distance is tapered down to a relatively smaller cross section wherein the spatial extent of the guided mode is substantially constant or expanding from the relatively larger to the relatively smaller waveguide cross section. The invention may e.g. be useful in applications such as fibre lasers or amplifiers, where light must be coupled efficiently from pump sources to a double clad fibre.

A laser system capable of efficient production of high energy sub-nanosecond pulses in the 2-15 μm spectral region is disclosed. Diode pumped solid state lasers are used as pump sources. The system design is simple, reliable and compact allowing for easy integration. The laser system includes a combination of compact solid-state ˜1 micron laser sources, producing high power picosecond pulses, with optical parametric amplification and a quasi-continuous wave laser for seeding the amplification process that enables the efficient conversion of the high power ˜1 micron laser radiation to tuneable mid-infrared sub-ns pulses. New parametric processes are presented for achieving high gains in bulk nonlinear crystals. Furthermore, a method of exceeding the fundamental conversion efficiency limit of direct three wave mixing is presented. The compact and robust nature of this novel laser system opens up the use of high power and high peak power mid-infrared laser pulses to a wide variety of important medical and dental applications.

The invention relates to Mg-Li alloy with high strength and its preparation techniques. It especially relates to Mg-Li alloy strengthened by quasi-crystalline phase and its preparation techniques, which can solve problems of alloy strengthening. Mg-Li alloy with low density, high strength and good plasticity is prepared by reasonable choosing of alloy elements and introducing quasi-crystalline phase into alloy base. The alloy is two-phase alloys of Mg-Li alloy in alpha-Mg and beta-Li phase areas. Component and content of the alloy are 5.5-11.5% Li, 0.5-15% Zn, 0.1-8% Y, and the allowances are Mg, in which percent is weight proportion. The alloy is made by melting and subsequent processing of hot extrusion and its crafts are simple and convenient to operate. Properties of materials are as follows: tensile strength is sigma b=200-300MPa, yield strength is sigma 0.2=150-260MPa, elongation percentage isdelta=17-65% and density is 1.34-1.83g / cm3.

The chemical general formula of the material is expressed as follows: LixM1-xFePO4, where M is selected from Mg2+, Ca2+...P5+ etc. With conduction adulterant added, reaction at 500-900 deg.C for 10 hr. by using metal oxide, phoshpate, fluoride etc. and non saturated crystal of Li-Fe phoshpate through nonstoichiometric method obtains the crystal of Li-Fe phosphate with high conductivity, which can be expressed as LiFePO4-y. The formula of material prepared by using method of pressurized type substitution ion is LixM1-xFezM'1-z. The formula of material of solid power prepared by using method of solid phase reaction is as LixM1-xFezMn1-zPO4. The formula of anode material in nano structure prepared by using method of vacuum sputter deposition is LixFePO4-y, whose conductivity and discharge capacity can reach 10 to the power -2 S / cm and 240 Ah / g.

The invention discloses a terahertz pulse measurement-based burning temperature sensing device and a terahertz pulse measurement-based burning temperature sensing method. Laser is emitted from a femtosecond laser device, and is divided into reference laser and detection laser through a beam splitter, the detection laser is focused on a photoconduction antenna type terahertz emitter, terahertz pulses emitted by the terahertz emitter are focused on a ZnTe crystal through an off-axis paraboloid lens group; and the reference layer is collimated and is coincident with terahertz waves focused on the ZnTe crystal after passing through a semi-transmission and self-reflection mirror, parallel grating groups and a polarizing film, the terahertz waves are modulated by using Pockels effect of the ZnTe crystal, and image signals corresponding to collected first reference layer carrying terahertz pulse strength information and second reference laser not carrying the terahertz pulse strength information are input into a computer by a CCD (Charge Coupling Device) detector for subsequence processing. According to the invention, the precision and speed of the non-contact combustion measurement method are increased, and the non-contact measurement of combustion object temperature and temperature distribution is realized.

An on-line energy coincidence method for an all-digital PET system, comprising: a detection module conducting information collection on a scintillation pulse, forming a single event data frame and sending the single event data frame to an upper computer (S1); the upper computer conducting two-bit position distribution statistics on an incident gamma photon event and conducting position spectrum partition (S2); performing statistics on an energy distribution spectrum of each crystal bar, so as to acquire an energy correction value (S3); the detection module uploading a crystal bar partition data table and an energy peak correction data table (S4); starting information collection of on-line energy correction (S5); when an event is coming, according to a two-dimensional coordinate thereof, from the crystal partition table, searching for a crystal bar number corresponding thereto, and then, according to the crystal bar number, searching for an energy correction value from the energy correction table (S6); and sending data passing the energy coincidence to the upper computer (S7). The method achieves fully automatic and fast on-line energy coincidence, and not only achieves the requirements of the variable structure PET for the fully automatic and fast correction, but also filters useless data in a transmission medium to a greater degree at the same time, thereby achieving the purpose of increasing a valid data bandwidth.

A method for ensuring the structural integrity of III-nitride opto-electronic or opto-mechanical air-gap nano-structured devices, comprising (a) performing ion beam implantation in a region of the III-nitride opto-electronic and opto-mechanical air-gap nano-structured device, wherein the milling significantly locally modifies a material property in the region to provide the structural integrity; and (b) performing a band-gap selective photo-electro-chemical (PEC) etch on the III-nitride opto-electronic and opto-mechanical air-gap nano-structured device. The method can be used to fabricate distributed Bragg reflectors or photonic crystals, for example. The method also comprises the suitable design of distributed Bragg reflector (DBR) structures for the PEC etching and the ion-beam treatment, the suitable design of photonic crystal distributed Bragg reflector (PCDBR) structures for PEC etching and the ion-beam treatment, the suitable placement of protection layers to prevent the ion-beam damage to optical activity and PEC etch selectivity, and a suitable annealing treatment for curing the material quality after the ion-beam treatment.

The invention belongs to fields of chemical industry, materials and optics, and relates to a structural color film material used in a large area and a method for preparing the same. Water-based inorganic nano-particles, monodisperse polymer emulsion and a non-essential addition agent are compounded by an in-situ polymerization method or blending method to obtain nano-composite emulsion, and the obtained emulsion is coated on the surface of a substrate; and moisture is volatilized, the three-dimensional ordered nano-structural color film material is prepared, and the color of the material can be regulated in a visible light area without adding any pigments. The structural color film material has the advantages of simple preparation, complete aquosity, safety, innocuity, easy large-area construction, good transparency, strong adhesive force and high heat resistance, can be directly coated on surfaces of glass, metal, ceramic, concrete, plastic and the like, and is used for bionics, decoration, printing, color display, photonic crystals, wave filtering, personal care, fabric fibers, coating, anti-counterfeit, optical sensors, photoelectric conversion materials and the like.

The invention relates to an inorganic scintillator material of formula Lu(2−y)Y(y−z−x)CexMzSi(1−v)M′vO5, in which:M represents a divalent alkaline earth metal and M′ represents a trivalent metal, (z+v) being greater than or equal to 0.0001 and less than or equal to 0.2,z being greater than or equal to 0 and less than or equal to 0.2;v being greater than or equal to 0 and less than or equal to 0.2,x being greater than or equal to 0.0001 and less than 0.1; andy ranging from (x+z) to 1.In particular, this material may equip scintillation detectors for applications in industry, for the medical field (scanners) and / or for detection in oil drilling, The presence of Ca in the crystal reduces the afterglow, while stopping power for high-energy radiation remains high.

The invention discloses a tapered photonic crystal quantum cascade laser for outputting near-diffraction-limited beams and the manufacture method thereof. The laser comprises a substrate, as well as a lower waveguide layer, an active area, an upper waveguide layer, an upper cover layer, an upper contact layer, an ohmic contact layer, an electrical insulation layer, a front side electrode and a rear side electrode on the substrate. The laser has the ridge-shaped mesa double-grooved waveguide structure, wherein the ridge-shaped mesa structure includes a main control oscillation area with a uniform ridge width and a gain amplification area with a tapered structure. The photonic crystal structure is used for providing a distributed feedback waveguide manufactured between the upper contact layer and the ohmic contact layer. The tapered photonic crystal quantum cascade laser can acquire singe-mode near-diffraction-limited beam output. The waveguide structure with the combination of the ridge-shaped mesa and the tapered gain amplification area can greatly reduce the far-field divergence angle, thereby improving the output power while obviating the heat dissipation problem that is difficult to avoid for the similar wide-ridge large-power devices.

This invention relates to controlled preparation of fine particles such as nano-crystalline films and powders with at least one solvent being in a supercritical state. It provides methods, measures, apparatus and products produced by the methods. In other aspects, the invention relates to further treatment of formed particles such as encapsulation of formed primary particles, and methods and measures for collection of formed substances in a batch wise, semi-continuous or continuous manner.

Improvements to the acquisition and replay systems for direct-to-digital holography and holovision are described. A method of recording an off-axis hologram includes: splitting a laser beam into an object beam and a reference beam; reflecting the reference beam from a reference beam mirror; reflecting the object beam from an illumination beamsplitter; passing the object beam through an objective lens; reflecting the object beam from an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form an off-axis hologram; digitally recording the off-axis hologram; and transforming the off-axis hologram in accordance with a Fourier transform to obtain a set of results. A method of writing an off-axis hologram includes: passing a laser beam through a spatial light modulator; and focusing the laser beam at a focal plane of a photorefractive crystal to impose a holographic diffraction grating pattern on the photorefractive crystal. A method of replaying an off-axis hologram includes: illuminating a photorefractive crystal having a holographic diffraction grating with a replay beam.

The invention relates to a new method for measuring an ultrashort light pulse spectral phase in the field of information optoelectronics and a device thereof. According to the method, a time delay minus T with polarity is introduced between two quasi-monochromatic light components with frequency Omega generated by the chirped stretching of a pulse to be detected; an additional time delay plus T, which is introduced between two quasi-monochromatic light components due to a pulse stretcher, is compensated to be in synchronization with the pulse to be measured and generate two sum frequency lights together with the pulse through a sum frequency crystal; respective power spectra and coherent spectra without interference fringe are acquired through a spectrometer. The phase difference between the two sum frequency lights is calculated by the three spectra through formulae. A spectrum phase curve of the pulse to be measured is calculated by adopting a concatenated method. The method can accurately determine the phase difference polarity of the pulse spectrum, and provide the simple, real-time, rapid and accurate measurement method and the device thereof for measuring the ultrashort optical pulse spectral phase.

The invention relates to nano-crystalline Fe3O4 particles with high absorption capacity and a preparation method thereof which belong to the field of material science. The microstructure of the particles comprises equiaxed nano-grains, and the particle size of the nano-grains is 5-100nm; the average particle size is 8-25nm, and the saturated magnetization MS is 6.7-7.2 multiplied by 10<minus 3>A / m. The preparation method is as follows: solution containing ferric ions and ferrous ions is prepared, ammonia solution is added under nitrogen atmosphere, ultrasonic waves are transmitted to carry out the ultrasonic dispersion, and heating, stirring and reaction are carried out; solids are washed till neutral by water under the condition of a magnetic field; water is removed by drying after the centrifugal separation. The invention utilizes the simple chemical reaction co-precipitation technology and combines the ultrasonic stirring, the centrifugal separation, the vacuum drying and other technologies to obtain the Fe3O4 powder materials with the average particle size of 8-25nm and the higher saturated magnetization.

The invention relates to an adjustable photonic crystal optical fiber terahertz waveguide, which comprises a coating consisting of a plastic material and air holes formed in a triangular period. The air hole in the center of the coating is used as a fiber core. The radius of the fiber core is greater than the radii of the other air holes in the coating. Nematic liquid crystals sensitive to the temperature are filled in the fiber core. The refractive index of the liquid crystals is greater than the refractive index of the coating. The refractive index of the liquid crystals can be changed by controlling the temperature of the working environment of the liquid crystals, so that a propagation mode, an effective mode field area and a zero dispersion range of an optical fiber are flexibly controlled. The defect that when the conventional photonic crystal optical fiber waveguide is produced, the optical properties and the transmission characteristics of the conventional photonic crystal optical fiber waveguide cannot be changed is overcome. A structure parameter of a photonic crystal optical fiber for the terahertz waveguide is at the millimeter order of magnitude. Compared with a visible light or infrared band photonic crystal optical fiber, the photonic crystal optical fiber for the terahertz waveguide is easier to prepare.

A bi-directional pulsed ring laser that produces bi-directional light pulses that interact in such a way that they are phase conjugated. A nonlinear substance, such as a nonlinear crystal or fluid, that has an index of refraction that is dependent upon light intensity is located near a beam waist of the laser cavity to provide a self-lensing effect. Methods for reducing dead band beyond observable limits are also provided. The increased sensitivity of the bi-directional pulsed ring laser provides application in detecting magnetic susceptibility by detecting the change in phase between the arrival times of the bi-directional pulses at a modulator and the electrical signal of the modulator to determine the change in frequency of a coil that has magnetic susceptibility.

The invention relates to a device and a method for testing a nonlinear polarization coefficient and an absorption coefficient at a terahertz band. Laser is split into one path of pump light and one path of probe light by a beam splitter, wherein the probe light is reflected by a reflector group with an adjustable light path, is attenuated by a metal attenuation piece used for adjusting the beam intensity of incident laser and then is reflected to a high resistance silicon chip by the reflector; the pump light split by the beam splitter is reflected to enter a terahertz generation device so as to generate terahertz collimating light and the generated terahertz collimating light is focused on a sample rack at a focus position by a parabolic mirror by virtue of a terahertz polarizing plate, and the terahertz is converted into parallel light which is reflected to the high resistance silicon chip by another parabolic mirror; and the two paths of light are coincided at the high resistance silicon chip, are focused to a detection crystal by the parabolic mirrors, are focused to reach a Wollaston prism by virtue of a 1 / 4 wave plate after being scattered by using a convex lens and are respectively focused to two photoelectric detectors. A test sample only needs to be arranged at the position of the sample rack or the detection crystal in a light path, namely the nonlinear polarization coefficient and the absorption coefficient of the sample at the terahertz band can be tested.

A new class of high-alloy metals is invented. The metals possess an amorphous, nano crystalline, or combined amorphous-nano-crystalline structure and are reinforced, stabilized and hardened with a framework formed by predominantly sp3-bonded carbon, also known-as diamond like carbon. Optionally, other alloying nonmetallic elements selected from the group of Si, B, O, N may additionally stabilize the structure. The disclosed high-alloy metals comprise a metallic matrix which may include iron, nickel, chromium, refractory, and various other metals. These materials are very stable, and do not suffer a structural degradation up to relatively high temperatures. The disclosed high-alloy metals have the properties of high hardness, corrosion and wear resistance, and low friction. They have a wide range of applications as protective coatings on a wide variety of materials in various industries. They may be further applied as magnetic and electronic devices, such as field emission cathodes. Some of these alloys possess high emissivity, and their electrical conductivity may be varied in a relatively wide range.

The invention discloses a branch controllable titanium dioxide nanotube array thin film and a preparation method thereof. The thin film consists of an array of a titanium dioxide nanotube formed by connecting a main tube and a branch tube in series; the thickness of the thin film is 1-100mum, and the porosity factor is 40-60 percent. The preparation method comprises the following steps: preparinga main tube electrolyte according to the proportion that the mole ratio of ammonium fluoride to glycol to water is 0.05-0.15:17.7:0.015-0.025, and preparing a branch tube electrolyte according to theproportion that the mole ratio of hydrofluoric acid to glycol is 0.15-0.25:17.7; then firstly, putting one surface of a titanium sheet in the main tube electrolyte to serve as the anode; carrying outanode oxidization under the conditions that the DC voltage is 55-65V and the temperature is 0-35 DEG C for 0.5-6h; then using the glycol to clean the anode; subsequently, putting the surface which isanodized in the branch tube electrolyte to serve as the anode, and carrying out anode oxidization under the conditions that the DC voltage is 30-120V and the temperature is 0-35 DEG C for more than 30min, thereby preparing the thin film. The thin film can be widely used for fields of dye-sensitized solar cells, gas sensors, photolytic water hydrogen production and photonic crystal.

This invention relates to oxyhalogenide photocatalytic materials and their preparation methods, belongs to photocatalytic materials area. This invention using solid phase or liquid phase prepared oxyhalogenide photocatalytic materials, characterized in its chemical composition of BiOX, X=Cl, Br, I, [Bi2O2]with[X] structure layer along the c-axis direction mutual piled up a layered crystal structure. BiOX (X = Cl, Br, I) of preparation have superior photocatalytic properties; can degraded organic dyes and organic hazardous gases, sterilization and photolysis aquatic hydrogen. Load Ag and Pt and other electronic affinity metal nm particles, can greatly enhance the material photocatalytic properties.

The invention relates to a femtosecond laser carrier envelope offset frequency lock system based on a heterodyne interferometric method. The system is characterized by comprising a femtosecond laser light source system, an acousto-optic modulator, a controllable optical path retardation device, a light splitting prism, a first photoelectric detector, a phase lock amplifier, a phase difference voltage conversion device and a PID controller. Heterodyne interferometry can be conducted on first-level phase-shift diffraction light modulated by the acousto-optic modulator and zero-level diffraction light which is not modulated, and after mixing of interference signals with different wavelengths, direct-current level lock pulse envelope alignment is achieved; optical frequency comb envelope offset frequency is locked by means of interference signal phase, the linear process does not exist, high non-linear optical fibers, frequency doubling crystals and the like are not needed, and the system is simple in structure and low in requirement for laser energy.

The invention provides a light emitting diode of white light with photonic crystal. The light-emitting dioxide comprises a substrate, an n-type contact layer, an active luminescent layer, a p-type contact layer. The active luminescent layer is located in the middle of the n-type contact layer and the p-type contact layer. The multiple-hole shape photonic crystal is arranged on the surface layer of the light-emitting dioxide, fluorescent powder with a nanometer quantity is filled inside the hole, and a transparent electrode is covered on the surface. The light-emitting dioxide is arranged inside the hole of the surface layer photonic crystal. The filling particle size is yellow, red or green fluorescent powder with a nanometer quantity; the surface of the photonic crystal is covered by the indium tin oxide (ITO) transparent electrode.

The invention relates to a preparation method of as-reduced ammonium tungsten bronze nanoparticles and belongs to the field of inorganic oxide materials. Under the condition of solvothermal, organic long-chain high-boiling-point acid is used as reaction medium, an organic tungsten source and organic high-boiling-point amine are used as raw materials, and ammonium tungsten bronze nanoparticles are produced through one-step control in the non-water environment. A sample prepared by the preparation method is hexagonal ammonium tungsten bronze nano-crystal; the size of the nano-crystal is adjusted in a range of 80-500 nanometers; the form of the nano-crystal is even; the particle size distribution is narrow; chemical valence state of the nano-crystal is mixture of W6+ and W5+; the nano-crystal has rich free electrons. In addition, the sample prepared by the preparation method has high capacity of absorbing near infrared; the film containing the nanoparticles is effective in shielding 780-2500 micrometers near infrared and is highly permeable to visible light.

The invention includes a composite material for use in a security device including a radiation diffracting component that exhibits a first optical effect and a photochromic component that exhibits a second optical effect. The composite material is particularly suited for use in authenticating articles, such as currency.

The invention provides a pulse infrared differential absorption laser radar system for detecting a carbon dioxide concentration profile, which comprises a laser emitting subsystem, an optical receiving subsystem and a data acquisition processing subsystem, wherein the laser emitting system comprises a seed laser, an Nd: YAG laser, a dye laser, a first reflecting mirror, a first half-reflecting half lens, a second half-reflecting half lens, a frequency doubling crystal, a difference frequency crystal, a first spectroscope and a wavelength control unit. The system can not only detect column concentration of atmospheric CO2, but also can obtain CO2 concentration profile distribution on a vertical path, particularly atmospheric CO2 concentration information near a boundary layer, and has important significance for carbon cycle research. The system has the advantages of low technical requirements, high stability, high detection precision and easy popularization, and is an important means for achieving atmospheric CO2 concentration profile measurement.

The invention discloses a dual-chirp optical parameter amplification method and device for broadband laser pumping. An initial laser source generates narrow-band laser which is divided into two beams, wherein the beam with the high energy is adopted as narrow-band pumping light, and broadband chirp pumping light is obtained after a spectrum widening device, and the light is emitted into a nonlinear crystal through a dichroic mirror; the beam with the low energy enters a super-continuum white light generator and a chirp mirror pair to obtain broadband chirp seed light, is emitted into the non-linear crystal through the dichroic mirror, and is coupled with the broadband chirp pumping light to be subjected to optical parameter amplification; finally, periodic magnitude pulse width femtosecond idler frequency light is obtained through a beam splitter and a pulse compressor. The spectrum widening broadband chirp pumping light is adopted, and the more frequency components are obtained; the broadband chirp pumping light and broadband chirp seed light dual-chirp scheme is adopted, and the instantaneous frequency correspondences are opposite, so that the spectral brand width of output idler frequency light is increased, and the femtosecond idler frequency light output of the periodic magnitude pulse width is achieved.