Method and system for generating orbital angular momentum light beam with high transmission and conversion efficiency

Abstract

The invention belongs to the technical field of orbital angular momentum light beam generation, and discloses a method and a system for generating an orbital angular momentum light beam with high transmission and conversion efficiency. A dielectric metasurface is utilized to generate an orbital angular momentum light beam with high efficiency and different orbital angular momentum states of the orbital angular momentum light beam are regulated and controlled. The method specifically comprises the steps of: regulating and controlling different orbital angular momentum states through the q valueof a metasurface, meanwhile, regulating and controlling a phase parameter phi through the thickness of the metasurface, the refractive indexes of a fast axis and a slow axis and the wavelength of incident light, and conducting high-efficiency orbital angular momentum light beam conversion. The method for effectively generating high-quality orbital angular momentum light beams based on the metasurface is researched from two aspects of theory and experiment, and high-efficiency light beams with different orbital angular momentum states are generated by artificially designing two-dimensional dielectric metasurface regulation and control. Under the condition that the wavelength of an incident light beam is 633nm, the transmission efficiency reaches 50% or above, and the conversion efficiencyreaches 90% or above.

Description

technical field [0001] The invention belongs to the technical field of orbital angular momentum beam generation, and in particular relates to a method and system for generating an orbital angular momentum beam with high transmission and conversion efficiency. Background technique [0002] At present, the beam has a spin angular momentum related to polarization, and can also carry an orbital angular momentum related to the helical phase wavefront. Usually, this kind of beam carries a definite orbital angular momentum The beam is called the orbital angular momentum beam (or called the vortex beam), and its light field contains the phase factor where l is the topological charge. In recent years, the orbital angular momentum of light beams, as a new degree of freedom, has shown good applications in the fields of optical micro-manipulation, ultra-high-precision imaging (including super-resolution microscopy), spectroscopy, quantum nonlinearity, and quantum information communic...

AI Technical Summary

Problems solved by technology

[0005] To sum up, the problems existing in the prior art are: (1) The conventional methods are expensive, complex devices, poor quality of the vortex light field, and cannot adjust the phase and polarization of light on a sub-wavelength scale.

[0006] (2) The conversion system of the existing cylindrical lens mode converter is relatively complicated, and the device manufacturing difficulty is high (cylindrical lens). In addition, due to the fixity of the incident beam mode, it is difficult to flexibly generate Laguerre-Gaussian beams of different modes

[0007] (3) There is currently no effective method to generate high-quality OAM beams

The existing liquid crystal spatial light modulators have low efficiency (more diffraction orders) and low pixels

Traditional technical methods for large-scale optical components are no longer suitable for future integrated photonic devices

[0008] (4) Transmissive metasurfaces based on metal nanoantenna structures are all due to the resistance loss of metals, and the beam conversion efficiency is extremely low, so they cannot be directly cascaded.

OAM beam generation based on plasmonic metasurfaces is also affected by conversion efficiency and cannot be used in integrated optical circuits

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