Composite grating used for detecting multiplexing vortex light beams and measuring method

Abstract

The invention discloses a novel composite grating and a method and device using the grating to detect orbital angular momentum state of multiplexing vortex light beams. When the vortex light beams are irradiated to the composite grating, the orbital angular momentum state of the vortex light beams can be obtained by observation of the position where gauss beams occur in a far-field diffraction pattern. The measuring range of the orbital angular momentum state of the composite grating is -24 to +24, and the range can satisfy detection of multiplexing vortex light beams under most circumstances. Using the composite grating can rapidly detect all orbital angular momentum components of the multiplexing vortex light beams, and when different multiplexing vortex light beams are incident, a light path does not need to be readjusted, so the operation is extremely simple and convenient. The novel composite grating and the method and device using the grating to detect the orbital angular momentum state of the multiplexing vortex light beams are of great significance to research of future photo-communication, optical tweezers technology, quantum communication and the like.

Description

technical field [0001] The invention relates to the field of optoelectronic technology, in particular to a composite grating and a measurement method for measuring multiplexed vortex beams. Background technique [0002] The vortex beam is a new type of beam, which has a continuous spiral wavefront compared with the general Gaussian beam. Due to the uncertain phase in the center of the beam, there is a phase singularity, so the cross-sectional light intensity distribution is a hollow ring. Common vortex beams are Laguerre-Gaussian beams and Bessel beams. The spiral wavefront of the vortex beam is the eigenstate of the beam orbital angular momentum operator, and the eigenvalue of the orbital angular momentum state can be any non-zero integer, that is, there are infinitely many such eigenstates in theory, so it can form infinite dimension of the Hilbert space. In this way, a single photon can be used to carry infinitely many mutually orthogonal orbital angular momentum state...

AI Technical Summary

Problems solved by technology

Common diffraction gratings include single slit, triangular hole, forked grating, Damman vortex grating, etc., but these gratings still cannot meet the detection requirements of vortex beams

First of all, triangular holes, single slits, etc. can only detect a single vortex beam, and cannot detect multiplexed vortex beams; secondly, forked gratings, Damman vortex gratings, etc. can detect multiplexed Vortex beams, but the detection ranges of their orbital angular momentum states are -4~+4 and -12~+12 respectively. To detect higher-order vortex beams, it is necessary to increase the fork index for the fork-shaped grating, which is undoubtedly Increased the difficulty of production; for the Damman vortex grating, it is necessary to fabricate a 7×7 array of Damman gratings, but the overlapping interference of different modes in the array and the resolution of the spatial light modulator limit its practical application. use

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