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Hybrid phase grating for measuring perfect vortex beam and measuring method

A vortex beam and phase grating technology, which is applied in the optical field, can solve the problems that the perfect vortex beam cannot be measured well and the resolution of the detection result is low.

Pending Publication Date: 2020-10-27
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For example, the patent publication with the application number "201510566068.0" discloses a composite grating and measurement method for detecting multiplexed vortex beams. However, during the generation of perfect vortex beams, perfect vortex beams only appear In the vicinity of the Fourier plane, the traditional vortex beam measurement method is constrained by the Fourier plane, which leads to low resolution of the detection results and cannot measure the perfect vortex beam well.

Method used

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  • Hybrid phase grating for measuring perfect vortex beam and measuring method
  • Hybrid phase grating for measuring perfect vortex beam and measuring method
  • Hybrid phase grating for measuring perfect vortex beam and measuring method

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Effect test

Embodiment 1

[0039] Such as figure 1 Shown is a hybrid phase grating used to measure a perfect vortex beam: the hybrid phase grating exhibits radial vortex and angular gradient distribution, and there are both angular phase and radial phase; on the hybrid phase grating , when the angular phase parameter changes continuously, the grating will gradually change angularly along the center to the surrounding; when the radial phase parameter changes continuously, the vortex distribution of the grating will change in density. Define the geometric center of the hybrid phase grating as the origin, and the x-axis and y-axis are respectively parallel to the two adjacent sides of the grating; the slits of the grating are distributed in a spiral shape relative to the rectangular coordinate system;

[0040] Among them, the radial phase is used to compensate the axicon phase to realize the control of the radius size of the perfect vortex beam light intensity and to expand the energy of the perfect vortex...

Embodiment 2

[0047] A measurement method for measuring a perfect vortex beam, using the perfect vortex beam to be measured to irradiate the hybrid phase grating of embodiment 1, and obtaining the orbital angular momentum of the perfect vortex beam from the diffraction spot projected by the hybrid phase grating The order of the state and the positive and negative of the orbital angular momentum state; the number of dark fringes of the diffraction spot is the order of the orbital angular momentum state of the perfect vortex beam, and the direction of the fringes of the diffraction spot is the orbital angular momentum state of the perfect vortex beam positive or negative.

[0048] Such as figure 2 and 3 As shown, firstly, the direction of the light and dark fringes of the diffraction spot is related to the positive or negative order of the orbital angular momentum state of the incident perfect vortex beam. select as figure 1 The circle shown in is the irradiation position of the perfect v...

Embodiment 3

[0057] A measuring device for measuring a perfect vortex beam, used to realize the measuring method of Embodiment 2, specifically comprising a laser 1, a polarization controller 2, a collimator 3, a first liquid crystal spatial light modulator 4, and a Fourier lens 5 , pinhole diaphragm 6, convex lens 7, second liquid crystal spatial light modulator 8, focusing lens 9 and CCD camera 10.

[0058] The laser 1 is used to emit laser light;

[0059] The polarization controller 2 is placed in the laser light path emitted by the laser 1 for generating horizontal linearly polarized laser light;

[0060] The collimator 3 is placed in the laser light path emitted by the polarization controller 2, and is used to collimate the laser beam;

[0061] The first liquid crystal spatial light modulator 4 is placed in the laser light path emitted by the collimator 3, and is used to convert the collimated beam into a Bessel-Gaussian beam carrying an orbital angular momentum state;

[0062] The F...

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Abstract

The invention relates to a hybrid phase grating for measuring a perfect vortex beam and a measuring method, the hybrid phase grating presents radial vortex and angular gradient distribution, and an angular phase and a radial phase exist at the same time; the measurement method comprises the following steps: irradiating the mixed phase grating by adopting a perfect vortex beam to be measured, and obtaining the order of the orbital angular momentum state and the positive and negative of the orbital angular momentum state of the perfect vortex beam from diffraction spots projected by the mixed phase grating, wherein the number of dark stripes of the diffraction light spot is the order of the orbital angular momentum state of the perfect vortex beam, and the stripe direction of the diffractionlight spot is positive or negative of the orbital angular momentum state of the perfect vortex beam. The measuring method of the hybrid phase grating is simple and accurate, can measure the perfect vortex beam of any order orbital angular momentum state without being limited by the Fourier plane constraint effect, and enables the measurement result to have high resolution.

Description

technical field [0001] The invention relates to the field of optics, more specifically, to a hybrid phase grating for measuring a perfect vortex beam and a measurement method. Background technique [0002] The topological charge of the traditional vortex beam is proportional to the radius of the central bright ring and the angular momentum of the beam, which not only limits its application in wavelength division multiplexing and information encoding, but also makes the vortex with a large topological charge The application of light beams in coupling, transmission and other fields has become very difficult. To overcome this shortcoming, the concept of perfect vortex beams was proposed. Compared with the traditional vortex beam, the perfect vortex beam can maintain a constant annular intensity distribution and beam radius regardless of the change of its topological charge, and has a certain peak intensity radius, and each point in the light field has a clear orbit Angular mo...

Claims

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Application Information

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IPC IPC(8): G01J11/00
CPCG01J11/00
Inventor 李朝晖褚超赖昭宇刘志兵
Owner SUN YAT SEN UNIV
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