A method for determining the vortex direction of a partially coherent Laguerre-Gaussian beam

Abstract

The invention discloses a method for judging the vortex direction of a partially coherent Laguerre-Gaussian beam. The partially coherent Laguerre-Gaussian beam to be measured is divided into reference light and signal light by a spectroscope; the signal light passes through two mutually perpendicular cylindrical lenses, and travels a distance z, and then the cross spectral density of the signal light is measured by a correlation system The asymmetric spatial distribution of the light beam; the reference light passes through the beam analysis system to measure the light intensity spatial distribution of the beam. The asymmetric spatial distribution of the cross spectral density of the signal light measured above and the light intensity spatial distribution of the reference light are processed by a computer according to the first-order coherence vortex distribution characteristics of the partially coherent Laguerre-Gaussian beam, and the beam to be measured is obtained. First-order coherence distribution map. The deflection direction of the axis of symmetry of the profile corresponds to the direction of the vortex of a partially coherent Laguerre-Gaussian beam. The method for measuring the coherent vortex direction of the light beam provided by the invention does not need expensive instruments, the measuring device is simple, the judgment is intuitive, and the result is reliable.

Description

technical field [0001] The patent of the present invention provides a method for judging the vortex direction of a partially coherent Laguerre-Gaussian beam. The method can be applied to a partially coherent vortex optical system with low coherence, and belongs to the field of partially coherent optical measurement. Background technique [0002] Optical vortices appear as singular points in light fields. At this position, the amplitude of the light field is zero and the phase cannot be defined. Near the singular point of the light field, the isophase surface presents a spiral distribution. This helical phase distribution makes the optical vortex-carrying optical vortex beams have orbital angular momentum, and thus shows great application prospects in many nearby fields such as optical trapping, atomic manipulation, information storage, and quantum communication. The research on optical vortex develops rapidly and becomes an important branch of modern optics. [0003] In ...

AI Technical Summary

Problems solved by technology

The literature (Effect of spatial coherence on determining the topological charge of a vortex beam, APPLIED PHYSICS LETTERS 101, 261104 (2012)) proposed a method to measure the topological charge of a partially coherent vortex beam, but this method can only obtain the size of the vortex Unable to get vortex direction

At present, the method and device for experimentally measuring the vortex direction of partially coherent Laguerre-Gaussian beams are still in a blank state

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