28 results about "Periodic grating" patented technology

This invention belongs to the field of wavelength division multiplexing optical communication technology, specifically relating to a reverse coupler based on a thin-film lithium niobate platform. The reverse coupler includes: a lithium niobate-on-insulator substrate, a first waveguide, a second waveguide, and a coupling region. The first and second waveguides are disposed in the device layer of the lithium niobate-on-insulator substrate. The first and second waveguides are arranged in parallel along the light propagation direction within the coupling region. A periodic grating perturbation structure is disposed on the first and / or second waveguides. This reverse coupler utilizes the grating perturbation structure to ensure that the modes of the two waveguides satisfy the phase matching condition. The optical signal input to one waveguide is reverse-coupled to the falling port of the other waveguide. Utilizing the large photoelectric coefficient of lithium niobate material, this reverse coupler can tune its spectrum under specific conditions by applying a voltage.

This invention relates to the field of mechanical seals, specifically a dynamic measurement method for the end face clearance of a mechanical seal, comprising the following steps: S1: setting a periodic grating structure on the non-sealing surfaces of the rotating and stationary rings of the mechanical seal; S2: acquiring a dynamic image sequence of the periodic grating structure during the operation of the mechanical seal; S3: processing the acquired dynamic image sequence to extract the phase information of the periodic grating structure and obtain phase change data; S4: calculating the relative displacement and relative rotation angle between the sealing end faces of the rotating and stationary rings based on the phase change data; S5: monitoring, providing early warning, and evaluating the state of the mechanical seal. This invention provides a dynamic measurement method for the end face clearance of a mechanical seal. This invention enables non-stop, non-contact online detection of the end face clearance of a mechanical seal.

Disclosed is a surface etched grating semiconductor laser with periodic pumping structure. The structure includes a lower doped dielectric layer, a multiple quantum well active layer, a ridge-shaped doped dielectric layer, periodic grating grooves formed on the ridge-shaped doped dielectric layer and a top electrical contact layer forming ohmic electrical contact with electrical contact regions between the grating grooves. Carriers are injected through the periodic electrical contact layer, flow through the electrical contact regions, spread laterally when reaching the bottom of the grating grooves, and then continue to spread to the multiple quantum well active layer. In a case of uniform distribution, a laser based on refractive index modulation is realized. In a case of non-uniform distribution, a laser with mixed modulation is realized by introducing additional gain modulation.

Optically Scanned Antenna and System Comprising Such an Antenna The present invention relates to an optically scanned antenna (10) comprising: - a light source (12) generating a beam, - a beam splitter unit (14) dividing the generated beam into N sub-beams, - a control unit (16) for the relative phase of the N sub-beams, - an integrated photonic circuit (11) comprising an array of extractors (34), the extractors (34) being arranged in a first two-dimensional periodic grating, each extractor (34) being adapted to extract a respective sub-beam from a plane of the integrated photonic circuit (11), - a lens array (20) arranged in a second two-dimensional periodic grating, the first and second gratings having the same arrangement, and - a displacement unit (22) for displacing the first and second gratings relative to each other. Figure for the abstract: Figure 1

A security element is arranged to safeguard valuable articles, featuring a motif layer based on a liquid-crystal material that forms a latent motif. The security element includes a first embossing varnish layer on a carrier film, with a motif layer partly on this varnish, based on nematic liquid crystals. A second embossing varnish layer covers the surface. The facing surface of the first varnish has an embossing with at least two regions featuring different alignment structures, creating a second latent motif. These alignment structures include an aperiodic grating with varying grid spacing. The motif layer, forming a first latent motif, overlaps the second latent motif regions. The nematic liquid-crystal material is aligned by the motif-forming regions, producing a discernible motif when viewed through a polarizer. The second varnish layer also has an embossing for a micro-optical relief structure and reflection-enhancing coating.

The invention relates to a high-sensitivity streak camera ultrafast scanning image enhancement and noise reduction method, and belongs to the technical field of ultrafast imaging and signal processing. The method mainly comprises the following steps of: performing spatial modulation on three-dimensional image data coded by a spatial coding element through a periodic grating; carrying out compression imaging on the modulated three-dimensional image data by the streak camera to form a two-dimensional observation image; an ADMM-TV algorithm is adopted to carry out image decoding, and a three-dimensional image containing a periodic modulation structure is recovered; after the three-dimensional image is reconstructed, effective fringe information in the modulated image is further extracted, high-frequency modulation residues are removed, and denoising of the interference fringe image is achieved. Physical separation of signals and noise is achieved through periodic grating modulation, high-frequency interference such as space charge noise can be restrained, the signal-to-noise ratio and contrast ratio of images are improved, and accuracy and stability of diagnosis of an ultrafast imaging system of a VISAR speed interferometer are improved.

Disclosed is a hybrid integrated single-longitudinal-mode narrow-linewidth compound cavity laser, which comprises: a distributed feedback gain chip (1), a micro-ring resonant cavity; the two ends of the distributed feedback gain chip are respectively coated with a first anti-reflection film (5) and a second anti-reflection film (6), and the internal reflection structure is a continuous periodic grating (3) along the cavity; the distributed feedback gain chip is a continuous uniform grating distributed feedback gain medium (4); and the micro-ring resonant cavity is a micro-ring resonant cavity with a reflection function. A working method is also provided.

This invention discloses an optical waveguide module, relating to the field of optical device technology. It includes a substrate, an optical waveguide layer on top of the substrate, and a buffer layer with a continuously curved, wave-shaped design between the substrate and the waveguide layer. This invention forms a stress-relieving structure based on the wave-shaped buffer layer, substrate, and waveguide layer, achieving thermal expansion coefficient matching and bending stress dispersion between the substrate and the waveguide layer. Simultaneously, combined with various adhesion enhancement layers, it ensures the long-term stability of the multi-layer interface. Furthermore, the input coupling layer employs a composite design of a blazed grating and a subwavelength grating, significantly improving the coupling efficiency from visible light to near-infrared. The output coupling layer achieves wide field-of-view output through a gradient periodic grating, adapting to large viewing angle requirements. Additionally, it integrates a modulator and a graphene thermal conductive layer, simultaneously solving the problems of high-speed modulation and heat dissipation, significantly improving the optical performance, thermal stability, and mechanical reliability of the optical waveguide module.

Some implementations described herein may provide an optical device. The optical device may include an optical emitter and an optical element aligned to the optical emitter. The optical element may include an oxidation aperture, one or more distributed Bragg reflectors (DBRs) disposed on the oxidation aperture, and a stacked periodic grating structure disposed on the one or more DBRs. The stacked periodic grating structure may include a set of layers. The set of layers may include alternating layers of a first material and a second material. The stacked periodic grating structure may have a selected period, depth, and fill factor that are selected to achieve greater than a threshold level of optical field confinement in a transverse direction of an optical field emitted by the optical emitter.

The invention relates to the field of mechanical seal, in particular to a dynamic measurement method for a mechanical seal end face gap, which comprises the following steps of: S1, arranging periodic grating structures on non-sealing surfaces of a moving ring and a static ring of a mechanical seal; s2, in the operation process of the mechanical seal, collecting a dynamic image sequence of the periodic grating structure; s3, processing the obtained dynamic image sequence, extracting phase information of the periodic grating structure, and obtaining phase change data; s4, the relative displacement and the relative rotation angle between the sealing end faces of the movable ring and the static ring are calculated based on the phase change data; and S5, monitoring, early warning and evaluating the state of the mechanical seal. The invention provides a dynamic measurement method for a mechanical seal end face gap. According to the invention, non-stop and non-contact on-line detection of the mechanical seal end surface gap can be realized.

The application provides a wavelength-selective infrared emitter device controlled by ultrafast laser and voltage, which comprises a first phase change material layer, a dielectric layer, a second phase change material layer, a metal reflection layer, a silicon substrate and a conductive layer from top to bottom; by means of layered superposition design of nonvolatile phase change material and volatile phase change material, surface micro-nano structure control and optical resonant cavity control are spatially separated, so that structure reconstruction and cavity length conversion bear different spectral control tasks respectively, thereby breaking through the problem that the control freedom degree of single phase change material is limited; that is to say, the application adopts ultrafast laser to perform local phase change control on the first phase change material layer, so as to realize writing or erasing of a surface periodic grating structure, and by means of applying voltage, the second phase change material layer is subjected to phase transition, so as to adjust the equivalent optical cavity length of the Fabry-Perot cavity, and finally the spectral shaping ability and control flexibility are improved, and wavelength-selective control can be realized.

The invention discloses a SiC micro-nano chute grating and a method for processing the SiC micro-nano chute grating based on ion implantation induction and electric spark, and the method comprises the following steps: S1, processing by adopting a silicon carbide substrate, then depositing a Cr / SiO2 composite mask layer on the substrate, exposing, developing and etching to form a Cr / SiO2 composite mask structure with a periodic grid pattern; s2, introducing ions into the exposed SiC region as an n-type dopant by adopting a large-angle inclined ion implantation method to form a conductive modified region, and obtaining a locally modified silicon carbide substrate; and S3, adopting electric spark machining to stably form a single-pulse-scale directional corrosion pit in the target ion implantation region, and realizing linear scanning etching along the grid bar direction to obtain the SiC micro-nano chute grating with the nano-scale groove structure. According to the method, the problems of low processing efficiency, poor processing surface quality, poor morphology control and the like of the SiC substrate grating are solved, and directional induction etching with a specified side wall inclination angle is realized.

The invention relates to the technical field of spectrum detection, in particular to a Raman and fluorescence shared spectrum detection system and method.The system comprises an optical fiber convergent mirror, a Raman and fluorescence color separation piece, a double-optical-fiber assembly, a double-collimating-mirror assembly, a double-cycle grating, a double-convergent-mirror assembly, an image intensifier and an area array detector; and all the components are sequentially conducted according to a light path to form a complete structure. According to the method, after being converged and separated by laser excitation mixed light, the mixed light is transmitted and collimated by double optical paths, is synchronously dispersed by the double-cycle grating, is parallelly converged by the double convergent mirrors, and is finally synchronously acquired by the area array detector for photoelectric conversion. The system solves the problems of high cost, complicated operation, serious spectral interference and the like in the prior art, has the advantages of integration, synchronous detection, high resolution, low interference, light weight, miniaturization and high stability, and can be widely applied to multiple fields of deep space exploration, biomedicine and the like.

The invention provides a semiconductor laser and a preparation method thereof, and relates to the technical field of semiconductor lasers, the semiconductor laser comprises an epitaxial wafer, a ridge waveguide and periodic grating structures are arranged in a P-type limiting layer of the epitaxial wafer, and the periodic grating structures are distributed on the two sides of the ridge waveguide; the periodic grating structure comprises a plurality of ridge strips arranged in parallel and notch grooves located between the adjacent ridge strips, and the ridge strips are uniformly arranged along the length of the epitaxial wafer and are parallel to the ridge waveguide; according to the semiconductor laser, the periodic grating structures are arranged on the two sides of the ridge waveguide in the P-type limiting layer of the semiconductor laser, and each periodic grating structure is provided with a plurality of ridges and notches, so that the high-order lateral mode of the semiconductor laser is effectively regulated and controlled, and the periodic grating structures are simple in structure and low in cost. And the complexity of the photoetching process and the preparation difficulty of the semiconductor laser are reduced.

The invention discloses a diffraction grating for improving the diffraction efficiency of an extreme ultraviolet interference exposure mask and a manufacturing method thereof, and the method comprises the steps: preparing a periodic grating structure on a substrate, and obtaining a basic diffraction grating; and etching the substrate in a non-grating area by taking the periodic grating structure in the basic diffraction grating as a mask pattern to obtain a target diffraction grating with a periodic structure. According to the diffraction grating manufacturing method and the prepared diffraction grating, on the premise that the basic geometrical characteristics of the grating are kept unchanged, the composite optical interface is formed by periodically modulating the substrate structure, and due to the fact that the interaction between light and the structure can be enhanced through the composite optical interface, the energy coupling efficiency in the diffraction grating is improved; therefore, the diffraction efficiency of the extreme ultraviolet interference exposure mask is improved.

This invention provides a silicon-based grating structure, fabrication method, and mid-infrared dual-color filter device for mid-infrared resonant filtering. The structure includes: a silicon-based substrate; an anti-reflection stacked structure disposed on the silicon-based substrate, the anti-reflection stacked structure being composed of a material with low absorption in the mid-infrared band; and a periodic grating layer disposed on the anti-reflection stack, the grating layer being composed of a silicon-based dielectric material with low light absorption in the mid-infrared band. The grating structure achieves a peak transmittance of >90% and an average transmittance of >85% in both the 3.0±0.1μm and 5.0±0.1μm bands by using diffraction coupling to excite guided mode resonance in conjunction with the anti-reflection stacked structure.

The invention relates to a Bragg grating device based on CO2 gas tuning and a preparation method, and belongs to the technical field of integrated photonics devices. The Bragg grating device comprises a single-mode fiber, a Bragg grating structure and a tuning medium; the single-mode optical fiber comprises a fiber core and a cladding; the Bragg grating structure is formed on the end face of the single-mode fiber; the Bragg grating structure comprises at least one supporting structure, a periodic grating structure fixed by the supporting structure and a hollow channel penetrating through the periodic grating structure; and the tuning medium is CO2 gas and is filled in the hollow channel. The micro grating with the built-in tunable gas cavity is integrally manufactured through two-photon polymerization 3D printing, and dynamic wavelength tuning with high precision, low loss, wide range and quick response of the device is realized by utilizing the low-loss refractive index regulation and control characteristic of CO2 in a specific infrared band.

The application belongs to the field of biochemical test, and particularly relates to a silver particle gold nanometer grating flexible substrate and a preparation method and application thereof. The polycarbonate layer in DVD or CD is used as a stamping mold, a three-dimensional periodic nanometer grating structure is prepared by stamping on a polyvinyl chloride (PVC) film, a gold layer is plated on the PVC, silver nanoparticles are uniformly decorated on the surface of the gold nanometer grating by using an interface self-assembly method, and the flexible substrate is prepared. The research results show that the electromagnetic field of the substrate is greatly enhanced, the uniform distribution of the silver nanoparticles and the periodic grating structure of the substrate enable the substrate to generate high-density and uniformly-distributed surface enhanced Raman scattering (SERS) hot spots, and the sensitivity and accuracy of detection are greatly improved. The application has the advantages of simple process, low cost and suitability for large-scale preparation, and provides a feasible idea for large-area preparation of a SERS substrate with high sensitivity, uniform signal and good stability.

The utility model provides a reticulated hinge loose-leaf and a book type certificate, the reticulated hinge loose-leaf comprises a first surface layer, a fabric layer and a second surface layer which are sequentially arranged from top to bottom, a plurality of reflective surfaces are hot-pressed at warp and weft overlapping positions on the surface of the fabric layer so as to present a latent image grid window with a preset shape in a preset area, and the reflective surfaces are reflective surfaces. Periodic gratings are formed at the positions, corresponding to the latent image grating windows, of the fabric layer, so that latent image patterns are shown on the surface of the fabric layer, and the first surface layer and the second surface layer are arranged on the two sides of the fabric layer in the thickness direction respectively to wrap the fabric layer. According to the reticulated hinge, the fabric layer is arranged as the center layer, and the latent image-text is formed at the overlapping position of the warp and the weft of the fabric layer, so that the reticulated hinge has excellent anti-counterfeiting performance and production convenience while having excellent physical properties such as tear resistance, flexibility and sewability, can be widely applied to the fields of various book type certificates, bills, packages and the like, and has wide application prospects. The application range is effectively widened, the practicability is enhanced, and cost reduction and efficiency improvement of enterprises are promoted.

This disclosure provides a dual parallel slit waveguide mode converter and its fabrication method. The device includes: a substrate, a buried oxide layer formed on the substrate, and a chip layer formed on the buried oxide layer. A waveguide structure is etched on the chip layer from one end to the other. The waveguide structure includes a periodic grating, a transition region, and an active modulation region connected sequentially. A dual parallel slit structure is formed in the active modulation region. The periodic grating is used to convert light into vertically coupled emission, and the transition region and active modulation region are used to convert the optical field mode in the waveguide structure into a dual-slit waveguide mode. This dual parallel slit waveguide mode converter has high coupling efficiency, low coupling loss, and small device size, making it easy to package.

The application discloses a kind of two-dimensional periodic grid sandwich plate structure acoustic vibration coupling system acoustic vibration characteristic analysis method, belong to structural acoustic analysis technical field.This method constructs the two-dimensional periodic grid sandwich plate structure acoustic vibration coupling system by upper and lower two plate structures, intermediate orthogonal grid rib and closed acoustic cavity, this acoustic vibration coupling system model has two-dimensional periodic cell structure, improved Fourier series is used to describe plate vibration displacement and acoustic cavity sound pressure, auxiliary function is introduced to ensure boundary continuity, based on energy method and Rayleigh-Ritz method, the Lagrangian function of coupling system is established, and the acoustic vibration characteristic prediction equation of acoustic vibration coupling system model is derived.The application is suitable for two-dimensional periodic grid sandwich plate structure periodic structure with arbitrary boundary condition and arbitrary cell number, with the advantages of high calculation efficiency, good convergence, strong model universality, etc., and can be used for vibration and noise reduction design of high-speed train carriage wallboard.

The invention discloses a moire-based power equipment temperature monitoring system and method. The moire-based power equipment temperature monitoring system comprises a temperature sensing device, an image preprocessing module, a moire feature extraction module and a temperature measurement and calculation module, a camera is used for detecting a moire visual mark which deforms along with the temperature change of the power equipment in the temperature sensing device; according to the invention, the temperature change of the power equipment is described as the change of the ratio of the projection frequency of the moire visual marked one-dimensional periodic grating calculated according to the moire characteristics on the imaging plane of the camera to the reference projection frequency, and the real-time temperature of the measured power equipment can be output.

A fiber amplifier is provided, including a pump laser (202), a pump and signal combiner (203), and a few-mode doped fiber (204). The pump laser (202) is configured to output pump light. The pump and signal combiner (203) is configured to couple input few-mode signal light and the pump light into the few-mode doped fiber (204). Refractive indexes of a fiber core of the few-mode doped fiber (204) are distributed to be gradient along a radial direction of a cross section, the fiber core is etched with periodic gratings along an axial direction, and periods of the gratings satisfy a phase matching condition. The fiber amplifier achieves strong coupling and co-amplification between optical signal modes, thereby reducing a differential gain between mode groups.

This invention relates to the field of array signal processing, specifically to a dynamic beamforming method for a uniform circular frequency diversity array sonar. The method includes: constructing a uniform circular frequency diversity array; configuring nonlinear frequency offsets in the form of natural logarithms for each array element; and transmitting a multi-carrier composite signal for each element, composed of multiple logarithmically offset single-frequency signals superimposed; calculating the complex weighting coefficients of each single-frequency signal based on the desired beam pointing and desired distance; and synthesizing a dynamic beam. This invention eliminates the phenomenon of periodic grating lobes in the beam over distance through nonlinear multi-carrier frequency offset design, solving the range-azimuth coupling problem; simultaneously, through the multi-carrier superposition mechanism, it significantly suppresses sidelobe levels and energy tails, improving the system's anti-interference capability; the constructed beam model strictly follows the physical laws of sound wave propagation, accurately characterizing the dynamic propagation characteristics of the beam.

The embodiment of the invention provides a panoramic head-up display device. The panoramic head-up display device comprises an image source display screen; the light ray modulation component is arranged on the light emitting side of the image source display screen and comprises a transparent substrate; the periodic grating structure is formed on the surface of the transparent substrate and is composed of light-transmitting stripe areas and light-shading stripe areas which are alternately arranged; the sum of the light-transmitting seam width a of the light-transmitting stripe area and the width b of the light-shading stripe area is the period T of the periodic grating structure, T is larger than or equal to 2 * the size of a single pixel unit, and a is smaller than or equal to 0.5 T, so that spatial separation of parallax image light of the left eye and the right eye is achieved; the surface of the shading stripe area is covered with a microprism structure, and the microprism structure is configured to reflect or absorb incident external ambient light so as to eliminate ambient light interference; and the reflection imaging assembly is used for receiving the image light after light splitting processing of the light modulation component and reflecting the image light to form a virtual image with a stereoscopic visual effect.

The application discloses a large-angle projection method and system of multiple MEMS galvanometer scanners, and a medium, wherein a high-speed photoelectric converter is placed between adjacent projection units; a galvanometer is driven to vibrate, and a laser is driven to emit point laser; the point laser emitted by the laser sequentially passes through a collimating lens and a linear prism, and is then incident to a surface of the galvanometer, and is reflected to a scanning object surface through the galvanometer, so that a periodic grating pattern is formed; the time delay of the driving signals of multiple lasers is adjusted, and the high-speed photoelectric converter is combined, so that the projection boundaries of two adjacent galvanometers are aligned; the time delay of the driving signals of the multiple lasers is adjusted, so that the phases projected by the multiple projection units are continuously coded; a camera is triggered to acquire the grating pattern; and three-dimensional information of the scanning object is generated based on the grating pattern; the application has the advantage of a larger FOV than a single MEMS galvanometer projection scheme, a projection scheme with a large depth of field and a large projection angle is obtained, and a low-cost scheme can be provided for a large-view-field three-dimensional scanning.

The present disclosure provides a mid-infrared thermal emitter comprising a phononic substrate, a dielectric layer bonded to the phononic substrate with a periodic grating structure formed thereon, and a membrane heater integrated with the phononic substrate. The thermal emitter is configured to produce narrowband coherent emission in the mid-infrared wavelength range between 10 micrometers and 12 micrometers with a quality factor greater than 100. The disclosure also provides a method of fabricating a coherent light-emitting metasurface for mid-infrared applications by creating a composite structure through forming a bonded interface between a dielectric layer and a phononic substrate, thinning the composite structure to a desired thickness, and forming periodic grating patterns in the dielectric layer to create a metasurface supporting off-gamma point Friedrich-Wintgen bound states in the continuum for coherent light emission in a wavelength range between 3 micrometers and 50 micrometers.

The invention relates to the field of array signal processing, in particular to a dynamic beam forming method based on uniform circular ring frequency diversity array sonar. The method comprises the following steps: constructing a uniform circular ring frequency diversity array, configuring nonlinear array element frequency offset in a natural logarithmic form for each array element, and transmitting a multi-carrier composite signal formed by superposing a plurality of logarithmic frequency offset single-frequency signals for each array element; and calculating a complex weighting coefficient of each single-frequency signal based on the expected beam direction and the expected distance, and synthesizing a dynamic beam. According to the invention, through the nonlinear multi-carrier frequency offset design, the phenomenon that periodic grating lobes appear on the distance of beams is eliminated, and the problem of distance-azimuth coupling is solved; meanwhile, by means of a multi-carrier superposition mechanism, sidelobe level and energy trailing are remarkably restrained, and the anti-interference capacity of the system is improved; the constructed beam model strictly follows the physical law of sound wave propagation and correctly represents the dynamic propagation characteristics of the beam.