A Method for Generating Orbital Angular Momentum States of Multiple Coaxial Orbits at One Time

Abstract

The invention discloses a method for generating a plurality of coaxial orbital angular momentum states at one time, comprising the following steps: Step 1: Gaussian light from a laser is collimated by a collimator, and then sent to a beam deflection device; Step 2: passing Controlled by the controller of the beam deflection device, the Gaussian beam is deflected at different angles. After passing through the collimation system composed of multiple lenses, the outgoing Gaussian beam is irradiated on different positions of the circular array vortex Damman grating. The beam transmitted by the arrayed vortex Damman grating is converted into multiple coaxial orbital angular momentum beams with different topological charge values, and multiple concentric circle patterns are displayed on the focal plane. The invention applies beam deflection and an improved circular array vortex Damman grating to the field of orbital angular momentum beam generation, and realizes a novel rapid generation method for multiple coaxial orbital angular momentum states.

Description

technical field [0001] The invention relates to the field of orbital angular momentum, in particular to a method for generating multiple coaxial orbital angular momentum states at one time. Background technique [0002] Orbital Angular Momentum (OAM) is one of the frontiers and hotspots in the field of quantum optics in recent years. In classical electromagnetic field theory, the angular momentum of the electromagnetic field is divided into spin angular momentum related to circular polarization and orbital angular momentum related to the space helical phase structure. During free-space transport, the spin angular momentum (SAM) and orbital angular momentum (OAM) remain unchanged. In 1992, Allen et al pointed out that for a beam with a helical phase factor exp(ilθ), each photon has The orbital angular momentum of , where l is the azimuth index of the beam, also known as the topological charge, the value can range from negative infinity to positive infinity, and its size de...

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Problems solved by technology

The traditional Damman grating produces a square diffraction field distribution, which is limited in some special occasions

[0007] In the prior art, the application publication number is CN101726868A, which discloses a method and device for realizing beam orbital angular momentum state multiplexing encoding, specifically disclosing lasers, polarizers, beam expanders, spatial light modulators, wave plates, Fourier Transform transmission, on the rear focal plane of the Fourier transform lens, form multiple beams in different orbital angular momentum states that are evenly distributed on the circumference centered on the optical axis of the incident light. The method is relatively complicated and the device cost is high.

Application publication number CN104280802A discloses a composite Damman vortex grating, the composite Damman vortex grating is composed of two basic topological charges ±l 0 The Damman vortex grating is a binary pure phase modulation device that is alternately combined from the inside to the outside according to the equal-width annular region. However, the composite Damman vortex grating can only produce multiple petal-shaped topological charges. spot

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