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中国物理学会期刊

Λ型四波混频中光学涡旋的相干转换及其相位演化

Coherent Transfer and Phase Evolution of Optical Vortices in a Λ-Type Four-Wave Mixing System

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  • 本研究基于一个双泵浦非简并四波混频结构,将光涡旋编码于任意输入光束的相位信息中,探究了生成光束的相位分布及其对系统参数的依赖。采用一阶微扰理论求解与原子介质极化相关的密度矩阵元,建立了生成的探测光与共轭光在介质内传输的耦合波方程,获得两光场拉比频率的解析表达式,模拟了共振情况下光学涡旋在光束间的相干转换。研究进一步重点揭示了频率失谐、退相率对涡旋光相位分布的影响。文中指出双光子共振时,可通过减小退相率来补偿单光子失谐引起的涡旋光相位失真;双光子失谐时,原子系统的相干条件被破坏,涡旋相位分布更容易畸变,且退相率越小畸变越显著。本工作为原子介质内实现高保真的光学涡旋操控提供了可靠的理论依据与优化策略,对推进基于轨道角动量的高维量子通信与信息处理具有重要意义。

    The aim of this paper is to explore high-fidelity phase-front transfer for optical vortices via four-wave mixing. Based on a dual-pump non-degenerate four-wave mixing configuration, an optical vortex is encoded in the phase of an arbitrary input beam. We investigate the phase profile of the generated beam and its dependency on the system parameters. Using first-order perturbation theory, we solve the density matrix elements related to the atomic medium polarization, establish the coupled-wave equations for the propagation of the generated probe and conjugate beams within the medium, and obtain analytical expressions for the Rabi frequencies of the two optical fields. The coherent transfer of optical vortices among beams is simulated. Furthermore, the research highlights the impact of frequency detuning and dephasing rate on the vortex phase distribution. The results indicate that frequency detuning not only affects the strength of light-atom interaction and the efficiency of four-wave mixing but also modulates the vortex wavefront of the generated beams, leading to phase distortion. Reducing the dephasing rate of the system ensures that high-fidelity coherent mode transfer of the optical vortex can be achieved even under single-photon detuning. Conversely, when the system coherence is better preserved, two-photon detuning induces more pronounced phase distortion in the vortex beam. Therefore, to achieve high-fidelity optical vortex transfer, it is necessary to minimize both the dephasing rate and the two-photon detuning. These findings provide an optimized scheme and theoretical foundation for the experimental realization of high-fidelity optical vortex transfer, offering significant reference value in the application field of vortex four-wave mixing, such as high-dimensional quantum communication and information processing based on orbital angular momentum.

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