Vortex beam orbital angular momentum high-order mode detection system and method thereof

Abstract

The invention discloses a vortex beam orbital angular momentum high-order mode detection system and method, and relates to the technical field of optical communication. The structure of the system is as follows: a first laser, a beam expanding collimator, a first polarization beam splitter and a first spatial light modulator interact in sequence to obtain a vortex beam to be measured; a second laser and a second polarization beam splitter interact front and back to obtain a second auxiliary Gaussian beam; the first spatial light modulator and the second polarization beam splitter interact with the beam splitter to obtain a composite beam to be measured; the beam splitter, the second spatial light modulator, the lens and the receiver interact in sequence to detect the composite light beam to be detected, and a first far-field diffraction intensity mode and a second far-field diffraction intensity mode are obtained in sequence; the first controller controls the first spatial light modulator. The second controller controls the second spatial light modulator and the receiver and displays the detection result. According to the invention, spiral stripes can be recognized more clearly, and a higher-order OAM mode can be detected; the structure is simple and easy to realize.

Description

technical field [0001] The invention relates to the technical field of optical communication, in particular to a detection system and method for a high-order mode of orbital angular momentum of a vortex beam. Background technique [0002] Vortex beams (Vortex beams) are beams with a helical form in the propagation direction of the wave front, and the beam has a helical phase factor Carry orbital angular momentum (Orbital Angular Momentum, OAM), the orbital angular momentum carried by each photon is lh, where is the direction angle, l is the topological charge value or the order of the orbital angular momentum, h is the modal value (also called mode value or eigenvalue) of OAM, and the helical wavefront and phase singularity are its two main features. [0003] With the rapid development of optical communication technology and the wide application of multiplexing technology, people have higher and higher requirements for channel capacity and transmission rate. OAM optical...

AI Technical Summary

Problems solved by technology

However, these methods basically need to adjust the off-axis parameters of the grating and optical filters to achieve better recognition results; in addition, when detecting the state of high-order OAM, because the obtained stripes are non-uniform stripes, the stripes on both sides The light intensity distribution is higher than the middle, the stripes on both sides are wider, and the stripes in the middle are thinner. If the topological charge value of OAM is too high, it will exceed the receiving range of the receiver and the stripes cannot be seen clearly.

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