13 results about "Waveguide dispersion" patented technology

The invention discloses a micro-ring modulator with a large free spectral range and a design method of the micro-ring modulator, and belongs to the field of optoelectronic devices. A micro-ring resonant cavity corresponding to the micro-ring modulator comprises an annular waveguide, and the width of the annular waveguide is an optimized width value, so that the integral value of the group refractive index of an optical mode in the annular waveguide along a closed optical path of the annular waveguide is minimized, and meanwhile, the width is ensured to be smaller than a cut-off width supporting high-order optical mode propagation. Through the design of accurately regulating and controlling waveguide dispersion, the free spectral range of the device can be maximized on the premise of ensuring single-mode work. In addition, an asymmetric electro-optical modulation structure can be arranged on the annular waveguide so as to be matched with a distorted optical mode, and high modulation efficiency is guaranteed. The micro-ring device with ultra-large FSR, high bandwidth, high efficiency and compact size can be realized, and the micro-ring device has important application value in the field of high-density optical interconnection.

The invention discloses a broadband circular waveguide TE01 mode exciter based on a crossed ridge waveguide, and relates to the technical field of microwaves. The exciter comprises a rectangular waveguide four-path power division feed structure for dividing the power of a TE10 mode into four paths, a crossed ridge waveguide TE22 mode forming structure for synthesizing the four paths of TE10 modes into a crossed ridge waveguide TE22 mode, and a circular waveguide TE01 mode forming structure for converting the crossed ridge waveguide TE22 mode into a circular waveguide TE01 mode. By introducing the crossed ridge waveguide structure, the directional regulation and control of waveguide dispersion are realized, and the cut-off frequency interval between a working mode and a parasitic mode is remarkably improved, so that the bandwidth is expanded. A crossed fan-shaped structure is introduced to serve as a middle structure of the crossed ridge waveguide and the circular waveguide, the cut-off phenomenon caused by sudden change of the waveguide shape is avoided, and the working bandwidth is further expanded. The high-purity and high-efficiency broadband filter has the advantages of being high in purity, high in efficiency, wide in frequency band and high in compactness, meanwhile, the structure is simple, machining and assembling are easy, and good engineering practicability is achieved.

The present invention discloses a circular dichroism detection device, a preparation method thereof, and a detection method thereof. The circular dichroism detection device is a micro - spiral fiber grating, which comprises a plurality of completely identical micro - spiral fiber grating segments with a period of P. Each micro - spiral fiber grating segment comprises a plurality of gratings with a reference grating period of Λ0, wherein the period P and the reference grating period Λ0 satisfy: Λ0 = λ0 / Δn, P = λ 0* Λ 0* s / |λ w ‑λ0|, λ w is the working central wavelength required for circular dichroism detection, λ0 is the reference central wavelength of the input left - and right - circularly polarized light, s is the waveguide dispersion correction factor of the original optical fiber for making the micro - spiral fiber grating, and Δn is the refractive index difference of the coupling mode. When the circular dichroism detection device of the present invention is immersed in a solution of a left - or right - handed chiral substance, the power changes of the left - or right - circularly polarized light with a specific wavelength passing through the detection device are different, and thus the type of chiral substance in the solution can be detected. The circular dichroism detection device of the present invention is simple to manufacture, has a fast detection speed, and high stability.

The invention relates to a method for solving dispersion characteristics of a spiral corrugated waveguide in an over-mode state. The method comprises the following steps of: determining an associated mode which can be coupled with a working mode and is coupled with the working mode; quantitatively describing a coupling process between the working mode and the associated mode; constructing a multimode coupling dispersion equation based on the coupling process between the working mode and the associated mode; and carrying out numerical solution on the multimode coupling dispersion equation by adopting an iterative algorithm to obtain a dispersion curve of the helical corrugated waveguide. Based on a coupling wave equation in a vector form, a mode coupling problem under a spiral ripple boundary condition is converted into an eigenvalue problem, a dispersion equation describing multimode coupling generalized is finally derived, numerical solution is carried out on the dispersion equation by adopting a fast convergence algorithm, and therefore a multi-mode coupling model is obtained. And finally, accurate and efficient analysis of the dispersion characteristics of the helical corrugated waveguide in the over-mode state is realized.

The invention relates to a pure finite element method, in particular to a pure finite element method for calculating a circumferential horizontal shear guided wave frequency dispersion curve. The method aims at solving the problems that an existing method needs complex programming and long calculation time, and consequently the solving process is complex and low in efficiency. The method comprises the following steps of: 1, adding a periodic boundary condition; establishing a finite element model of a pipeline periodic unit under the cylindrical coordinate system in finite element software; 2, parameterized scanning is carried out to solve the characteristic frequency; the invention belongs to the technical field of guided wave dispersion curve calculation.

The invention provides a dielectric waveguide dispersion suppression method and system based on channel middle section frequency spectrum shift, and the method comprises the steps: transmitting a to-be-transmitted signal to a dielectric waveguide channel middle section through a first dielectric waveguide channel, and generating a transmission signal affected by first waveguide dispersion; frequency mixing is carried out on the transmission signal and the double local frequency signal, a frequency mixing signal is generated, and the frequency mixing signal is a signal obtained after an upper sideband and a lower sideband of the transmission signal are exchanged; transmitting the frequency mixing signal through a second section of dielectric waveguide channel to generate a frequency mixing output signal influenced by second waveguide dispersion; the first-section dielectric waveguide channel and the second-section dielectric waveguide channel have the same physical length and dispersion characteristic, so that the dispersion of the first waveguide and the dispersion of the second waveguide are mutually compensated. The frequency spectrum shifting operation is introduced into the middle section of the channel to realize the exchange of the upper sideband and the lower sideband, so that the dispersion generated by the two sections of dielectric waveguide channels is mutually compensated, the dispersion effect is effectively inhibited, and the signal transmission distance is increased.

An optical pulse generating apparatus utilizing optical waveguide dispersion and a method thereof are disclosed. This apparatus includes a sine wave generator generating one of a plurality of sine waves and a phase modulator modulating incident light from a laser using the sine wave generated by the sine wave generator. This apparatus further includes a phase controller that controls the sine wave generator to generate one sine wave by transmitting sine wave information used in generation of an optical pulse selected by a user, and controls an optical waveguide connected to a phase modulator by transmitting optical waveguide information used in generation of the optical pulse to the optical waveguide connector. The sine wave information includes frequency information and amplitude information (or modulation index information) for generation of an optical pulse, and the optical waveguide information includes length information (or dispersion value information) for generation of an optical pulse.

The invention provides a zero dispersion flat optical comb system based on a Fabry-Perot cavity. The system comprises a first grating, a first progressive area, a resonant cavity, a second progressive area and a second grating which are sequentially connected along an optical path. The first grating and the second grating serve as reflecting end mirrors of the Fabry-Perot cavity and are used for providing optical feedback, grating parameters of the first grating and the second grating are adjustable, and the first grating and the second grating are used for regulating and controlling group velocity dispersion of the Fabry-Perot cavity to a zero dispersion point. The first progressive area and the second progressive area are respectively used for realizing mode matching between the first grating and the resonant cavity and between the resonant cavity and the second grating. The resonant cavity is used for providing a resonant channel and determining the free spectral range of the optical comb. The system is configured to directly generate an optical comb having a free spectral range at a zero dispersion point through a dynamic balance of a spectral filtering effect and a Kerr nonlinear effect. The defect that a broadband and ultra-flat optical comb cannot be directly generated due to the fact that an annular resonant cavity is difficult to actively regulate and control to a zero dispersion point due to waveguide dispersion solidification is overcome.

The disclosed method, device, equipment and medium for quickly calculating the dispersion curve of a viscoelastic anisotropic shale reservoir waveguide comprise: obtaining viscoelastic anisotropic medium parameters of a shale reservoir; calculating a frequency domain stiffness matrix based on a Kelvin-Voigt viscoelastic medium model and the viscoelastic anisotropic medium parameters of the shale reservoir; constructing a waveguide dispersion equation based on the frequency domain stiffness matrix and using a Thomsen-Haskell transfer matrix method; and solving the waveguide dispersion equation by using a fast recursive method to find roots and obtain a waveguide phase velocity dispersion curve and an attenuation coefficient curve in the viscoelastic medium, wherein the waveguide phase velocity dispersion curve and the attenuation coefficient curve are used to calculate a sensitivity function relative to different parameters. Therefore, the viscoelasticity and anisotropy of the medium are combined, which can effectively reduce errors in the description of the shale reservoir, thereby improving the accuracy of reservoir physical property parameter inversion based on waveguide dispersion properties.

The invention relates to the technical field of optoelectronic devices, in particular to a silicon nitride-based Euler bending spiral micro-ring resonant cavity structure and a construction method thereof, and the structure comprises a silicon substrate; the micro-cavity structure is arranged on the silicon substrate, a silicon nitride buried waveguide layer is arranged above the micro-cavity structure, the silicon nitride buried waveguide layer comprises a silicon oxide lower cladding, a silicon nitride waveguide and a silicon oxide upper cladding from top to bottom, and the micro-cavity structure comprises a coupling waveguide and a spiral micro-ring. The coupling waveguide completes evanescent wave coupling in the horizontal direction of the small-curvature structure on the periphery of the spiral micro-ring. Therefore, the problems that the non-uniformity of the thickness of a film of a related micro-ring resonant cavity structure is not beneficial to the realization of a large-size micro-ring resonant cavity, and the design result and the actual test result are seriously mismatched due to the non-uniformity of the thickness in application scenes with relatively high requirements on waveguide dispersion characteristics such as a micro-cavity frequency comb and the like are solved. And the reliability of the device is reduced.

The invention provides a finite element method for calculating a longitudinal modal guided wave frequency dispersion curve of a liquid-filled pipeline, belongs to the technical field of nondestructive testing, and aims to solve the problems that in an existing guided wave frequency dispersion curve solving method, solving is only carried out on a simple model with the periphery of the pipeline being vacuum but not having other media; the method comprises the steps that finite element software is used for establishing a geometric model of the three-dimensional axisymmetric liquid-filled pipeline, and the geometric model of the three-dimensional axisymmetric liquid-filled pipeline is used for solving the complex solid mechanics-fluid coupling model of the liquid-filled pipeline with a liquid medium; calculating a displacement vector generated in the liquid and the elastic wall when the guided wave propagates along the z axis of the pipeline; calculating a characteristic equation of the sound wave in the elastic pipeline and the viscous liquid under the condition of no volume force; theoretically simulating an infinitely long waveguide of the pipeline; obtaining a relationship between the index factor and the wave number; and calculating the phase velocity and group velocity of the guided wave based on the exponential factor and the wavenumber, and obtaining a frequency dispersion curve of the longitudinal mode of the liquid-filled pipeline.

The invention relates to the technical field of ultrasonic guided wave processing, in particular to a guided wave frequency dispersion compensation method and device based on a Fourier-based CAE network, and the method comprises the following steps: collecting an ultrasonic guided wave signal; constructing a convolutional self-encoding network model based on a Fourier basis; substituting the ultrasonic guided wave signal data into the convolutional self-encoding network model for training until the convolutional self-encoding network model tends to be stable; inputting the acquired ultrasonic guided wave signal data into the trained convolutional self-encoding network model, and outputting a coordinate with a maximum value; and taking a maximum value coordinate, converting the maximum value coordinate to a time domain again, combining the excitation signal, and performing frequency dispersion compensation on the ultrasonic guided wave signal to obtain a guided wave signal without frequency dispersion. According to the method, the Fourier basis is introduced into the auto-encoder, and a path for performing time-frequency information extraction by using the Fourier basis is added, so that the converted data has two characteristics of time and frequency, signal frequency dispersion compensation under the condition of multiple wave packets can be realized, and the effect is relatively good.

The application discloses a broadband stepped film waveguide dual circular polarizer, and belongs to the technical field of microwave and millimeter wave. The device comprises a left-handed circular polarization feed waveguide, a right-handed circular polarization feed waveguide, two 90-degree waveguide bends, a radiation waveguide and a stepped film. The two feed waveguides are connected to the radiation waveguide through the 90-degree waveguide bends. The radiation waveguide is composed of a square waveguide and a cross-shaped waveguide, and is divided into an input section, a polarization separation / forming section and an output section which are connected in sequence. The input section is divided into left and right cavities by a waveguide wall. The polarization separation / forming section is provided with the stepped film. The left and right cavity sections are completely fused in the output section. The application adjusts waveguide dispersion, significantly expands the interval between the working mode and the high-order mode, and realizes the broadband working of the stepped film waveguide dual circular polarizer. At this time, the polarization separation / forming section can realize a 90-degree phase difference in a short distance, which is beneficial to reducing the transmission loss of the device and improving the compactness of the device.