Device and method for simultaneously measuring topological charge and positive and negative of vortex beam

Abstract

The invention discloses a device and method for simultaneously measuring the topological charge size and positive and negative values of a vortex light beam. The device comprises an angular gradual-change attenuation piece which is used for the angular modulation of the amplitude of an electric field of a to-be-measured vortex light beam; a focusing lens which is used for focusing the modulated vortex light beam; and a CCD camera that is used for recording the focusing light intensity and obtaining the size and positive and negative information of the topological charge of the vortex beam to be measured through the distribution of the focusing light intensity. By means of the technical scheme, simultaneous measurement of the topological charge and the positive and negative values of the vortex beam to be measured is realized.

Description

technical field [0001] The present disclosure relates to a device and a method for simultaneously measuring the size and the positive and negative of the topological charge of a vortex beam. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] A vortex beam is a beam with a spiral phase structure, and its spiral phase structure can be expressed by the phase factor exp(-ilθ), where θ represents the azimuth angle of the vortex beam in the cylindrical coordinate system, and l is called The topological charge indicates the number of phase reversals within a wavelength range. When the phase is reversed counterclockwise, the topological charge is positive, otherwise it is negative. At the same time, each photon in the vortex beam carries The orbital angular momentum of is the reduced Planck constant. At present, the common vortex beams in the ...

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Problems solved by technology

Among them, the interferometry refers to interfering the vortex beam to be measured with a beam of reference light, and then obtaining the topological charge information from the interference pattern. The reference beam can be a plane wave or a spherical wave. The typical interference optical path structure is based on the Mach-Zehnder double beam. Interferometry, but the two-beam interferometry requires an ideal reference beam, which makes the detection device not compact enough, and the optical path is complex and very sensitive to environmental disturbances

The diffraction method refers to analyzing the far-field or focused light intensity distribution of the vortex beam through a special optical element. The optical elements here include: array small hole plate, circular hole, ring, triangular hole, prism, double slit , movable single slit, etc. In the case of some elements such as rings, further mathematical analysis of the diffraction light intensity is required, such as Fourier transform, etc. Although the structure of these specially made diffraction elements is relatively simple, the size accuracy and collimation are very demanding, and it is difficult to obtain the magnitude and sign information of the topological charge at the same time

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