弱散射介质中的传播不变传输本征模

中文摘要 AI 辅助

具有环形角谱的传播不变光束（PIBs）能在长距离传播中保持横向强度结构。本文研究散射不变模（SIMs）是否可同时具备散射不变性与传播不变性。我们针对弱、中、强散射介质，在正交环形基下测量自由空间与样品的传输矩阵（TMs），并识别出局域化散射不变模（LSIMs），其角谱主要局限于一个或少数相邻环。弱散射条件下，所考虑的128个环形局域化SIMs中有75个满足该标准，LSIMs表现出类贝塞尔传播特性；中散射条件下，过滤低强度光谱分量后可得到25个LSIMs，而强散射条件下未发现此类模。尽管模态串扰增加会逐步抑制环形局域化与无衍射行为，但在中、强散射区域，SIMs相比类高斯光束与贝塞尔光束在传播过程中保持了更高的横向强度相关性。这些结果表明，环形局域化使SIMs在弱散射时获得传播不变性，而即使该局域化消失，SIMs增强的传播鲁棒性仍可保留。

英文摘要

Propagation-invariant beams (PIBs) with annular angular spectra preserve their transverse intensity structure over extended propagation distances. Here, we investigate whether scattering invariant modes (SIMs) can simultaneously exhibit scattering and propagation invariance. We measure free-space and sample transmission matrices (TMs) in an orthonormal annular basis for weak, moderate, and strong scattering media and identify localized SIMs (LSIMs) whose angular spectra remain predominantly confined to one or a few neighboring rings. Under weak scattering, 75 of the 128 SIMs considered for annular localization satisfy this criterion, with LSIMs exhibiting Bessel-like propagation. Under moderate scattering, 25 LSIMs are recovered after filtering low-intensity spectral components, whereas none are found under strong scattering. Although increasing modal crosstalk progressively suppresses annular localization and nondiffracting behavior, SIMs retain higher transverse-intensity correlation over propagation than the Gaussian-like and Bessel beams in the moderate and strong regimes. These results show that annular localization enables SIMs to acquire propagation invariance when scattering is weak, whereas the enhanced propagation robustness of SIMs can persist even after this localization is lost.

发表机构

• Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México（墨西哥国立自治大学核科学研究所）

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