31results about How to "High pattern purity" patented technology

The invention discloses an axisymmetric-structure high-power coaxial over-mode surface wave oscillator which uses electromagnetic wave radiation of the terahertz wave band generated through wave-beam interaction as the basic working principle, according to high-current relativity theory electron beams and an over-mode coaxial slow wave structure, strong wave-beam interaction happens, and high-power terahertz waves are generated. The coaxial over-mode surface wave oscillator comprises a non-foil diode, the over-mode coaxial slow wave structure, a transitional wave guiding part and an output wave guiding part of a coaxial structure. The working mode of the over-mode surface wave oscillator in a wave-beam interaction zone is a TM01 mode, by mode converting of the transitional wave guiding part, transmission is carried out at an output wave guiding end of the surface wave oscillator in a TEM mode, the 0.14THz over-mode surface wave oscillator is designed through the structure, and the peak power of an output port can reach 115MW. The over-mode surface wave oscillator is suitable for generating the high-power electromagnetic waves in the terahertz wave band.

The invention discloses an inclined multi-path synthetic gyrotron traveling wave tube TE02 mode input coupler, and belongs to the technical field of microwave and millimeter wave devices. The input coupler comprises a power distribution part, an inclined multi-path synthesis part and a cut-off circular waveguide. According to the invention, a high-purity TE02 mode is coupled in a main circular waveguide by adopting an inclined multi-path synthesis structure, and by changing the number and position distribution of the branches of rectangular waveguides on the side wall of the main circular waveguide and the included angle between the branches of the rectangular waveguide on the side wall and the circular waveguide, the field distribution of the main competitive modes (TE01 and TE41) of a TE02 mode in the main circular waveguide is destroyed to improve impedance matching, so that the beneficial effects of effectively suppressing a parasitic mode, reducing a reflection coefficient, improving conversion efficiency and increasing bandwidth are achieved.

The invention discloses a 1[mu]m waveband column vector fiber laser based on a mode selection coupler. The laser comprises a pumping source, a wavelength division multiplexer, a gain fiber, an annulardevice, a single-mode Bragg grating, a first polarization controller, a second polarization controller, a mode selection coupler and a collimator. The output end of the pumping source is connected with the short wavelength input end of the wavelength division multiplexer. The output end of the wavelength division multiplexer is connected with the port 1 of the annular device through the gain fiber. The port 2 of the annular device is connected with the single-mode Bragg grating. The port 3 of the annular device is connected with the long wavelength of the wavelength division multiplexer through the first polarization controller and the mode selection coupler. The second polarization controller and the collimator are connected to the few mode fiber output end of the mode selection coupler.The laser is advantaged by high slope efficiency, slight insertion loss and high column vector laser polarization purity.

The invention discloses a groove-assisted double-step ring core optical fiber. The groove-assisted double-step ring core optical fiber comprises a ring core and an outer cladding; the ring core sequentially comprises a central cladding, a second-layer step ring, a first-layer step ring and an annular groove from inside to outside; refractive indexes of the first-layer step ring core and the second-layer step ring core are distributed in a double-step ring core shape; the first-layer step ring core is used for controlling optical fiber normalization frequency so as to regulate and control the number of modes; the second-layer step ring core is used for increasing the effective area of the modes so as to reduce the nonlinear coefficient of each mode of the optical fiber and suppress a radialhigh-order mode; and the double-layer step structure is used for mode regulation and control with higher degree of freedom. The optical fiber can support eight-order OAM modules, the effective refractive index difference between the modules is larger than 10<-4>, and module weak coupling transmission can be adopted. Four modes in the modules are in a degenerate state, and a fixed 4*4-scale MIMO algorithm can be used. OAM modes supported by the optical fiber are all radial first-order modes.

The invention provides a device and a method for generating columnar vector beams in optical fiber by utilizing an electrically-controlled tunable optical grating. By means of the linear polarization characteristic of the electrically-controlled tunable optical grating, efficient coupling between a linear polarization vector basic mode in a fiber core and TM01 and TE01 modes can be realized, and a columnar vector light field with strict radial and angular polarization characteristics can be generated. Complete coupling between the linear polarization vector basic mode and the columnar vector light field can be realized by optimizing the refractive index modulation degree of the electrically-controlled tunable optical grating. Columnar vector light can be generated in different wavelength positions of the optical fiber conveniently by adjusting and modulating the period of the electrically-controlled tunable optical grating. The adopted device is simple and has high columnar vector light field generation efficiency, the generated columnar vector light beams have high mode purity, meanwhile, different radial and angular vector light fields can be conveniently converted, and the columnar vector light field can be generated in different wavelengths by adjusting radio-frequency signals.

The invention discloses a novel gyrotron traveling wave tube input coupler, and belongs to the technical field of microwave and millimeter-wave devices. The novel gyrotron traveling wave tube input coupler comprises a coaxial structure, a cut-off circular waveguide, an output circular waveguide and a rectangular input waveguide, wherein the cut-off circular waveguide and the output circular waveguide are arranged at two ends of the coaxial structure respectively; the rectangular input waveguide is arranged on the side surface of the coaxial structure; a plurality of coupling gaps are arranged in an inner conductor of the coaxial structure; and a short-circuit branch rectangular waveguide is arranged on an E surface of the rectangular input waveguide. The short-circuit branch waveguide is arranged on the E surface of the rectangular input waveguide on the basis of a traditional gyrotron traveling wave tube. Reflection of the input coupler can be effectively offset by reasonably designing the position and structure parameters of the short-circuit branch waveguide; and the transmission efficiency of a high-frequency end is improved, so that the input bandwidth is effectively expanded.

The invention discloses a vortex light beam wavefront phase correction method based on a Gerchberg-Saxton algorithm. The method comprises the following steps: firstly, constructing an adaptive optical system transmission model based on a vortex beam, and simulating phase disturbance caused by atmospheric turbulence to obtain field intensity distribution of a distorted transmission beam and a detection beam in a time domain; and then taking the distorted detection light beam as the input of a vortex light beam wavefront phase correction method based on a Gerchberg-Saxton algorithm, iteratively calculating a random phase similar to atmospheric turbulence, and further obtaining a corrected phase mask. A spatial light modulator is loaded on a distorted OAM light beam, so that OAM light beam inter-mode crosstalk caused by atmospheric turbulence is relieved. The wavefront phase correction method is good in correction effect and can effectively improve the mode purity of transmitted LG light beams.

The invention discloses a hollow-core microstructure optical fiber with angular mode selectivity, and belongs to the technical field of optical fiber optics and application thereof. The hollow-core microstructure optical fiber includes a matrix material (1), a wrapping layer formed by arranging rounded hexagonal air holes (2) in the matrix material in a hexagonal periodic mode, and large air holes (3) in a fiber core area. The size of the large air hole in the fiber core area is equal to the size of an area formed by one air hole in the wrapping layer and two to four layers of air holes with the air hole as the center. The wrapping layer comprises twelve symmetry axes which form an angle of 30 degrees, the sizes of wrapping layer air holes of which the centers fall on the twelve symmetry axes are larger or smaller than those of air holes in other positions, but the shapes of the wrapping layer air holes are kept consistent with those of the air holes in other positions. According to the invention, through geometric parameter modulation of specific air holes in 12 radial directions of the wrapping layer, an angular mode selection function is achieved, so that the optical fiber only supports pure-state low-loss transmission of an angular mode in a working wave band.

The invention belongs to the technical field of microwave, millimeter wave and terahertz devices, and particularly relates to an ultra-wideband radial power divider based on a circular polarization TE11 mode. According to the basic principle that any linearly polarized wave can be subjected to vector decomposition into two orthogonal circularly polarized waves, a step-shaped partition plate is arranged at an input port in a circular waveguide along an output direction; the stepped partition plate is connected with the output port of the waveguide matching section and is in the same straight line with the gap between the waveguide matching sections and the gap between the input waveguides; by means of the structure that the width of the waveguide matching section is equal to the width of the gap between the waveguide matching sections, an input linear polarization TE10 mode vector is decomposed into two orthogonal circular polarization TE11 modes, the 90-degree phase difference of the orthogonal modes is achieved, and the TE11 modes show the rotating field characteristic. The rotating TE11 mode distributes electromagnetic energy to N paths of rectangular waveguides with equal power along with time, and ultra-wideband mode conversion and power distribution are realized. The device is simple in structure, easy to machine and high in conversion efficiency.