Device and method for efficiently generating square array vortex beams by utilizing binary phase plate

Abstract

The invention discloses a device and a method for efficiently generating a square array vortex beams by utilizing a binary phase plate. The device comprises a light source, a beam expanding and collimating mirror, the binary phase plate, a first Fourier lens, a filter and a second Fourier lens, wherein the expanding and collimating mirror is arranged in the light emitting direction of the light source, and is used for converting light from the light source into large-caliber parallel light beams; the binary phase plate is arranged at the rear end of the beam expanding and collimating mirror and is used for modulating a wavefront of a light field of the large-aperture parallel light beams; the first Fourier lens is arranged at the rear end of the binary phase plate, and converts the parallel light beams into frequency spectra of the light field at a rear focal plane of the Fourier lens; the filter is placed on the frequency spectral surface of the light field, allows symmetrical light spots at the central position to pass through, and performs phase modulation on the passed symmetrical light spots at the same time; and the second Fourier lens is arranged at the rear end of the filter and used for converting the symmetrical light spots after phase modulation into symmetrical parallel light beams with the same axial wave vector, and the parallel light beams interfere with one another to generate square array vortex light beams.

Description

technical field [0001] The invention discloses a method and a device for efficiently generating a square array vortex beam by using a binary phase plate. Background technique [0002] Because of its specific orbital angular momentum, vortex beam has a special dark hollow structure and spiral phase distribution, it has important application value in the fields of optical communication, particle manipulation, etc., and the vortex beam array is arranged according to a certain law A large number of vortex beams are assembled, and their special light intensity distribution and mechanical properties have important application values ​​in the fields of material processing, particle manipulation, and particle shunting. [0003] At present, the common methods for generating array vortex beams mainly include: helical phase filtering method, fractional Taber effect method, and multi-beam interference method. Among them, the helical phase filtering method adopts a typical 4f optical pa...

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Problems solved by technology

Among them, the helical phase filtering method adopts a typical 4f optical path, and a helical phase plate is placed as a filter at the spatial frequency plane of the system. The energy utilization rate of the array vortex beam is low, and the intensity of the array vortex beam diffuses rapidly when it deviates from the output surface of the system; After a well-designed complex periodic phase-only diffractive optical element, a periodic array of vortex beams can be obtained at a certain position behind the element. The advantage is that the energy utilization rate of the system is very high, but it can only be generated at a specific position. The intensity of the vortex beams in the periodic array deviates from the corresponding position, and the intensity of the vortex beams in the array will also quickly disperse; due to the inconvenient processing of complex periodic phase-only diffractive optical elements, for convenience, it is generally realized with a spatial light modulator. It will lead to a serious decline in the energy utilization rate of the system, and the large pixel size of the spatial light modulator will also affect the quality of the vortex beam; and the array vortex beam generated by the multi-beam interferometry has very good diffraction invariant characteristics , making the practical application prospect of the arrayed vortex beam more broad

[0004] However, the inventors found that in the past, the generation of square array vortex beams based on multi-beam interference was mainly realized through liquid crystal spatial light modulators, which greatly reduced the energy utilization efficiency of the system and severely limited the actual production of array vortex beams. Applications in life

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