398 results about "Nonlinear coefficient" patented technology

The invention concerns novel varistors based on zinc oxide and a method for making same, which consists in using as base products nanocrystalline powders obtained by high-intensity mechanical grinding and in subjecting the mixture resulting from said nanocrystalline powders a consolidating treatment such as sintering, in suitably selected temperature and time conditions so as to retain the smallest possible grain size of ZnO. The resulting varistors have a very fine homogeneous microstructure and an average grain size characteristically not more than 3pm, i.e. five times smaller than standard materials. Said novel varistors have a larger number of grain boundaries per unit length unit and therefore a much higher breakdown voltage. Said voltage is characteristically higher than 10 kV/cm and can reach 17 kV/cm which is almost one order of magnitude above the breakdown voltage of standard varistors. The non-linearity coefficient of the current-voltage curve is also improved, and is greater than 20 and can reach values as high as 60. Moreover, the leakage currents below the breakdown voltage of said varistors, are much lower.

The invention relates to a micro-ring waveguide optical device capable of realizing all-optical signal processing by utilizing a high-nonlinearity effect, and aims to overcome the defect that nonlinear coefficients are insufficient when a conventional micro ring performs all-optical signal processing. The provided micro-ring waveguide optical device comprises a straight waveguide and a parallel growth micro ring on a substrate, wherein the micro ring is an annular resonant cavity; the ridge waveguide part of the micro ring adopts a parallel slot structure instead of a single ridge waveguide structure; and the straight waveguide is coupled with the micro ring. According to the micro-ring waveguide optical device, one parallel slot micro-ring waveguide structure is innovated; and when light is coupled into the parallel slot micro-ring waveguide structure, the slot waveguide structure can well limit a light field, the light intensity of resonance light is enhanced greatly due to the resonance effect of the micro ring, accordingly, various nonlinear effects of the micro ring are enhanced, the threshold value is reduced, the efficiency is improved, and the device can be applied to the all-optical signal processing fields such as optical frequency comb, wavelength conversion, logic gate, format conversion and the like.

An optical fiber, which has a zero-material dispersion wavelength equal to or greater than 2 μm, and a high nonlinear susceptibility χ³ equal to or greater than 1×10⁻¹² esu, and uses tellurite glass having sufficient thermal stability for processing into a low loss fiber, employs a PCF structure or HF structure having strong confinement into a core region. This enables light to propagate at a low loss. The size and geometry of air holes formed in the core region, and the spacing between adjacent air holes make it possible to control the zero dispersion wavelength within an optical telecommunication window (1.2-1.7 μm), and to achieve large nonlinearity with a nonlinear coefficient γ equal to or greater than 500 W⁻¹ km⁻¹.

The invention discloses a photonic crystal fiber capable of transmitting 22 photon angular momentum modes. The photonic crystal fiber comprises a center fiber core, an annular high refractive index layer and an annular cladding, wherein the fiber core is a large air hole; the annular cladding comprises a cladding I, a cladding II, a cladding III and a cladding IV; the cladding I is composed of 36 square air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of a cross section of the optical fiber is 10 degrees; the cladding II is composed of 30 circular air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of the cross section of the optical fiber is 12 degrees; the cladding III is composed of 36 circular air holes in a circular uniform arrangement manner, and an included angle between every two adjacent square air holes relative to the center of a circle of the cross section of the optial fiber is 10 degrees; and the cladding IV is composed of 40 circular air holes in a circular uniform arrangement manner. According to the photonic crystal fiber disclosed by the invention, the quantity of OAM (Orbital Angular Momentum) modes supported by a waveband of 1500-1600nm reaches 22, crosstalk among the various modes is less, confinement loss of most of the modes is low (10<7>dB/m), and the photonic crystal fiber is small in dispersion and low in nonlinear coefficient.

The invention provides a metal plate micro-defect detection method based on nonlinear Lamb waves. The metal plate micro-defect detection method comprises the following steps of: S1, acquiring a phasevelocity frequency dispersion curve and a group velocity frequency dispersion curve of a metal plate; S2, acquiring an excitation frequency, Lamb waves of a specific mode and an incident angle of theLamb waves of the specific mode as model parameters according to the phase velocity frequency dispersion curve and the group velocity frequency dispersion curve; S3, deriving a relative nonlinear coefficient beta' according to the Lamb waves of the specific mode in the S2, wherein the relative nonlinear coefficient beta' is used for representing the depth of a defect; S4, establishing a nonlinearultrasonic test system according to the model parameters; and S5, testing the metal plate according to the nonlinear ultrasonic test system established in the step S4, judging whether the relative nonlinear coefficient beta' is reliable or not, and if so, representing the defects of the tested metal plate by utilizing the relative nonlinear coefficient beta'. According to the metal plate micro-defect detection method, the relative nonlinear coefficient beta' represents the defects of the tested metal plate, the defects of the metal plate can be effectively represented, and the detection precision is improved.

The invention discloses a preparation method of a copper-electrode zinc-oxide voltage-sensitive resistor, which comprises the following steps of: voltage-sensitive ceramic-body manufacture, copper-electrode slurry printing, copper-electrode drying and copper-electrode sintering and permeation, wherein the copper-electrode sintering and permeation are carried out under an oxygen-free atmosphere environment by adopting a chain-belt type tunnel electric furnace as production equipment. In the invention, the copper-electrode zinc-oxide voltage-sensitive resistor with qualified performances is manufactured by replacing noble-metal silver with base-metal copper as an electrode material and using special electrode sintering and permeating processes, so that the production cost is greatly saved. The preparation method has the following advantages that: 1. the process technology is suitable for the mass production of the copper-electrode zinc-oxide voltage-sensitive resistors; 2. all the electrical performances (comprising voltage nonlinear coefficient, leakage current, through-current capacity, energy tolerance and the like) of a product produced through the process technology can reach the level equivalent to a silver-electrode product, and the requirements of clients are met; and 3. the cost of the product is much lower than that of the silver-electrode product in the same specification.

The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines. Further, the present invention provides a light source comprising a plurality of continuous light sources of which at least one oscillates in a multimode; a multiplexer for multiplexing output light from the continuous light sources; and a nonlinear phenomenon producer for producing a nonlinear phenomenon on output light from the multiplexer so as to suppress SBS (Stimulated Brillouin Scattering).

The invention discloses a formulation of an AC zinc oxide resistance chip. The formulation is characterized by comprising the following additives and a main material ZnO by weight percentage: 4.0 to 4.9 percent of Bi2O3, 3.0 to 4.0 percent of Sb2O3, 0.5 to 1.0 percent of SiO2, 2.0 to 3.0 percent of Co2O3, 0.50 to 0.80 percent of Cr2O3, 0.50 to 0.80 percent of MnCO3, 0.70 to 0.90 percent of NiO, 0.03 to 0.05 percent of aluminum nitrate, 0.10 to 0.20 percent of glass dust, 0.07 to 0.10 percent of B2O3 and 85.0 to 88.0 percent of ZnO. The formulation of the resistance chip has the following characteristics and advantages: the nickel protoxide and the glass dust are introduced into the formulation, so that the stability and the aging performance of the internal structure of the resistance chip is more excellent; and 2, dosage of cobalt sesquioxide, dibismuth trioxide and diantimony trioxide are added in the formulation, the mixture ratio of each composition is more reasonable, and the non-linearity coefficient of the resistance chip can be improved, the pressure ratio is reduced, the circulation capability is improved, and the comprehensive performance is excellent.

The invention discloses an optically controlled optical PAM signal regeneration device comprising a power adapting unit, an optical clock control unit and a PAM reshaping unit, wherein the PAM reshaping unit is the core of a regenerator and is composed of a Mach-Zehnder interferometer MZI and a highly nonlinear fiber ring NOLM, for a to-be-regenerated degraded optical PAM signal, the level matching between the input degraded optical PAM signal and the PAM reshaping unit is accomplished by the power adapting unit, the optical clock signal power and the delay output by the optical clock control unit and a phase shifter in the MZI structure are adjusted, so that the PAM reshaping unit works normally, the loss coefficient, the optical fiber length, the nonlinear coefficient and other parameters of a highly nonlinear optical fiber in the NOLM structure, and the coupling coefficients of front and back couplers in the MZI structure are changed to design PAM reshaping units with different level numbers, and then the regeneration of the degraded optical PAM signal is accomplished. Therefore, the optically controlled optical PAM signal regeneration device disclosed by the invention can execute a reshaping and a re-timing function and has the advantages of flexible design of regeneration level numbers.

The invention relates to a method of applying Rayleigh waves in non-linear ultrasonic evaluation of surface damage of a metal material. The method comprises the following steps: 1) excitation and reception of Rayleigh waves; 2) detection of reliability of a testing system; 3) measurement of non-linear coefficients when the surface of a test piece has damage of different degrees; 4) repeatable operation of test. Compared to the method of using body waves for ultrasonic nondestructive test, the non-linear ultrasonic evaluation method provided in the invention has the characteristic that Rayleigh surface waves are especially suitable for measurement of non-linear coefficients of large-scale complex plate structures. According to the invention, it is only needed to carry out excitation and measurement of supersonic waves at one side of a structure during measuring, which enables measuring to be simple and easy; the Rayleigh surface waves have advantages favorable for measuring, e.g., concentration of energy on the surface of a structure, a long propagation distance, etc.; operation is simple and easy, so the method is especially suitable for on-site detection of structural elements; effective evaluation of early damage and degeneration of mechanical properties of a material structure can be realized by using the non-linear ultrasonic method.

The invention discloses a material acoustic non-linear coefficient measuring method through Relay surface wave, which comprises the following steps: adopting specific signal amplifier as signal source; assembling piezoelectric sensor on the rim of the detector piece directly to excite the Relay wave; using laser interferometer to gather the Relay wave signal on the gathered piece surface; proceeding Fuliye conversion for the gathered Relay wave signal rapidly; obtaining the basic frequency and high frequency component in the signal; affirming the relative acoustic non-linear coefficient of the material effectively and precisely.

The invention discloses a zinc oxide base high-potential gradient voltage-sensitive ceramic material and preparing method and application, which comprises the following parts: 100mol ZnO as main component, first accessory ingredient within Bi2O3, Co2O3, MnO2, Cr2O3, Ni2O3 with molar quantity at 0.5-1.2mol respectively, second accessory ingredient with 0.8-1.5mol Sb2O3, third accessory ingredient with 0.2-1.2mol Ho2O3 and or Er2O3, forth accessory ingredient with 0.002-0.005mol Al2O3. The preparing method comprises the following steps: blending each component together to make spraying slurry; spraying; drying; graining; proceeding dry pressing; moulding; sintering. The potential gradient of voltage-sensitive ceramic material is 300-500V/mm with non-linear coefficient is more than 50, which can be applied in the electric lightning arrester or other lightning protection overvoltage protection of electric electronic circuit due to strong pulse attack resistance ability.

The invention relates to a process method for preparing low residual voltage ZnO varistor ceramic and belongs to the technical field of residual voltage ZnO varistor ceramic machining; the residual voltage ZnO varistor ceramic preparation process is based on the sintering process and seeded solution growth and includes the raw materials of ZnO, Bi2O3, MnO2, Sb2O3, Co2O3, SiO2, Al (NO3) 3 9H2O and Cr2O3; the preparation method includes that: ZnO, Bi2O3 and Al (NO3) 3 9H2O in the raw material formula are adopted to be ground by a ball mill and dried as seed crystal raw material; the seed crystal raw material is placed in a high temperature electric resistance furnace for pre-sintering to from seed crystal lumps as the first step, and the seed crystal lumps are cooled to normal temperature in the furnace; and then the seed crystal lumps are ground by the ball mill again and sieved to obtain seed crystals; all remaining raw materials, the seed crystals and PVA solution are mixed and ground by the ball mill to be dried, sieved and granulated with water content and pressed into blanks; and the blanks are sintered and cooled to normal temperature in the second step. The process method not only can reduce grain resistivity and ZnO varistor residual voltage, but also restrains the increasing of current leakage and the decreasing of non-linear coefficient. The low residual voltage ZnO varistor ceramic has higher performance and is more suitable for industrial application.

Provided is a dispersion-shifted fiber for an optical parametric amplifier. The dispersion-shifted fiber is a silica-based optical fiber and has a large nonlinear coefficient and a small effective area. The dispersion-shifted fiber also reduces a bending loss and a splice loss due to a mode field diameter difference between it and a conventional single mode fiber. For this, the dispersion-shifted fiber comprises a rectangular core with a very small radius and a high refractive index, a depressed inner clad, and an outer clad with a ring. The core and/or the inner clad are/is doped with a heavy metal.

The invention discloses a high double-refraction photonic crystal fiber (PCF) comprising a fiber core and a cladding. Two small air holes are removed from the central part of an optical fiber so that an ellipse-like fiber core is formed; meanwhile, the structural arrangement of the air holes of the cladding is changed, and four pairs of large air holes and a pair of elliptic air holes are introduced to the cladding and connected to the fiber core, so that the optical fiber with the structure has double rotation symmetry, a cross-polarization mode is not degenerated again, and very high double-refraction is shown. Through changing the structure of the fiber core and adjusting the diameters of the large air holes and the ellipticities of the elliptic air holes within a certain range, the PCF is two orders of magnitudes higher than a common optical fiber due to the adoption of the mode of double refraction, and meanwhile, the optical fiber has a high nonlinear coefficient. The PCF provided by the invention has the advantages of simple structure, high double-refraction and high nonlinearity. The PCF with the structure can be used for manufacturing a polarization-preserving optical fiber and relevant optical fiber devices with proper nonlinearity or polarization characteristics.

The invention relates to a self-frequency-doubling all-solid-state yellow-light laser. The laser comprises an excitation source, a focusing system, a self-frequency-doubling crystal and a laser resonator, wherein the self-frequency-doubling crystal is a ytterbium-ions-doped rare-earth calcium oxoborate crystal and is cut along the maximum direction of the effective nonlinear coefficient of a non main plane of the crystal; the excitation source is a 900-980nm light source; and the laser resonator is composed of an input cavity mirror and an output cavity mirror, the input cavity mirror and the output cavity mirror are each provided with a medium membrane for inhibiting vibration of a 1020-1080nm wave band, excitation light is subjected to collimating focusing and is injected into the self-frequency-doubling crystal through the input cavity mirror, the self-frequency-doubling crystal absorbs energy of the excitation light to generate fundamental frequency light in the laser resonator, and the fundamental frequency light carries out selection wavelength frequency multiplication through the self-frequency-doubling crystal so that 570-590nm yellow-light laser is output. The laser provided by the invention has the advantages of high output power, simple and compact structure, low cost, high temperature adaptability and the like.

The invention discloses a mixed silicon rubber-based conductive nonlinear insulating material, relates to a rubber-based nonlinear dielectric material, and mainly solves the problems that the existing silicon rubber-based nonlinear dielectric material is low in breakdown strength and poor in physical-mechanical properties because a large amount of nonlinear functional filler is added. The nonlinear insulating material is made of a mixed silicon rubber, a nonlinear functional filler, white carbon black by gas phase method, nano-ferric oxide, diphenyl silanediol and organic peroxide, wherein the nonlinear functional filler consists of nano-zinc oxide, nano-silicon dioxide, nano-silicon carbide, a carbon nano-tube, conductive carbon black and nano-graphite. The prepared nonlinear insulating material has the advantages that the alternating-current breakdown strength is not smaller than 30kV/mm, the direct-current breakdown strength is not smaller than 60kV/mm, the maximum nonlinear coefficient is 6-18, the tensile strength is not smaller than 9.0MPa, and the breaking elongation is not smaller than 200%. The invention is mainly applicable to high-voltage composite insulating materials.

The invention discloses an adaptive digital signal processing algorithm for compensating optical fiber transmission nonlinear damages, and relates to the field of optical fiber transmission. The algorithm comprises following steps of setting three nonlinear coefficients after a receiving end receives signals; respectively substituting into an adaptive digital backward propagation algorithm for processing, thus obtaining three signal amplitude values as initial values; estimating the nonlinear coefficients by utilizing the strength variances of the signals, wherein after many times of iteration, an optimum nonlinear coefficient gamma <opt > for nonlinear compensation can be estimated; taking the optimum nonlinear coefficient gamma <opt > as the input of adaptive digital backward propagation; then stopping iteration; carrying out CR (carrier recovery) and decode processing to the signals, thus recovering the signals of a transmitting end; and calculating a BER (bit error ratio). The algorithm provided by the invention can be applied in coherent light communication system of an M-QAM (M-ary quadrature amplitude modulation) high order modulation format; the optimum nonlinear coefficient can be determined more precisely; and the algorithm complexity is reduced.

The invention belongs to the image processing technology field and provides a hyperspectral image nonlinearity solution blending method based on a neural network. By using the method, corresponding work of extracting an end member and acquiring end member abundance and a nonlinear coefficient can be effectively completed so that a solution blending effect is further increased. The method comprises the following steps of (1) inputting hyperspectral image data; (2) randomly generating a sufficient number of training samples and testing samples; (3) using the trained multilayer perceptron neural network to extract abundance and a nonlinear coefficient of a single pixel point in a hyperspectral image; (4) making the acquired abundance satisfy a corresponding constraint condition; (5) repeatedly carrying out solution blending on all the pixel points in the image and then stopping calculation; otherwise, returning to the step (3); and (6) evaluating the performance of the algorithm by calculating a reconstruction error and a spectral angle distance. The method is mainly used for image processing.

A nonlinear ultrasonic detection method for evaluating the thermo-oxidative ageing of an organic material comprises the following steps: building an organic material thermo-oxidative ageing damage nonlinear ultrasonic detection system based on a nonlinear acoustic detection system; respectively setting corresponding parameters of an excitation signal and a reception signal, and finely adjusting the corresponding parameters of the excitation signal and the reception signal by a time domain waveform signal observed and received by an oscilloscope; selecting the optimum work frequency range of a probe according to the frequency characteristic of the ultrasonic probe, and determining the initial frequency and the ending frequency of the swept frequency range; adjusting integrator gate parameters, carrying out frequency sweeping to obtain the change rule of an supersonic wave fundamental wave amplitude and a secondary harmonic amplitude with the frequency, and storing the change rule in a computer; calculating corresponding nonlinear coefficients of all frequency points in the swept frequency range, and calculating the accumulated nonlinear effect in the swept frequency range; and determining a corresponding relationship between the accumulated nonlinear effect and the thermo-oxidative ageing time of the organic material, and assessing the existence or not and the degree of the thermo-oxidative ageing damage of the organic material.

The invention relates to a zinc oxide varistor ceramic material doped with a composite rare earth oxide and a method for the production thereof, which belongs to the functional ceramic material manufacturing technique field. The ceramic material is characterized in that the zinc oxide varistor resistance material comprises the following compositions of 95 percent to 98 percent of ZnO as a main material, respectively 0.1 percent to 1.0 percent of MnO2, Co2O3, Bi2O3, Cr2O3 and Sb2O3, and 0.01 percent to 0.4 percent of composite rare earth oxide by molar percentage, wherein the composite rare earth oxide is one of Sc2O3, rare earth oxide Y2O3, La2O3, Ce2O3, Er2O3, Dy2O3 and Nd2O3 non-doped or doped with Al2O3. The invention increases the electric potential gradient of the zinc oxide varistor ceramic to between 1300 and 1600V/mm through adjusting the reasonable proportion of the composite rare earth oxide, and the non-linear coefficient is between 30 and 50 and the leakage current is between 2 and 20 mu A. The varistor ceramic of the invention can be used for making high grade lightning protector products with supervoltage electric systems.

The invention relates to high-performance zinc oxide composite ceramic voltage dependent resistor material and a preparation method, which belongs to the technical field of electronic ceramic preparation and application. The ceramics takes zinc oxide as main phase, adopts praseodymium oxide as nonlinear initial phase, adopts a small amount of oxides of Co, Cr, Fe or W as potential gradient and nonlinear reinforcing agent, and comprises the following components by mole percent: 80 to 95 percent of ZnO, 0.01 to 15 percent of Pr6O, 0.01 to 10.0 percent of CoO, 0.01 to 8.0 percent of Cr2O3, 0.0 to 5.0 percent of Fe2O3 and 0.0 to 3.0 percent of WO3. The material preparation method comprises the following processing step in sequence: mixing->high-energy ball milling->drying->mixing and pelletizing->sifting->compression moulding forming->sintering->silver-layer coating. The voltage dependent resistor material has the advantages that the crystal grain is fine, the microscopic structure is uniform, the potential gradient E (the potential gradient value corresponding to 1 mA/cm<2> current density) is increased to 570 to 750 V/mm, the nonlinear coefficient alpha is 24 to 32, and the leakage current IL (the current density value corresponding 75 percent E) is 0.004 to 0.006 mA/cm<2>, and has excellent over-all electrical properties. The voltage dependent resistor material can be used for manufacturing the lightning arresters of ultra high voltage/extra high voltage power systems, and can realize the miniaturization of the lightning arrester. The invention can also be used for manufacturing cell phones and household appliance chip or multiplayer chip voltage dependent resistors.