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Main Authors: Tang, Fangqing, Xiao, Xing, Chen, Lixiang
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.00295
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author Tang, Fangqing
Xiao, Xing
Chen, Lixiang
author_facet Tang, Fangqing
Xiao, Xing
Chen, Lixiang
contents The far-field intensity distribution of spatiotemporal Laguerre-Gaussian (STLG) modes propagating in free space exhibits a multi-petal pattern analogous to that observed in tilted Hermite-Gaussian modes. Here, we show that this phenomenon can be explained by the SU(2) symmetry of spatiotemporal Gaussian modes, which can support the irreducible representation of SU(2) group and enable the construction of the spatiotemporal model Poincaré sphere. We have also derived analytical expressions for the STLG mode with an arbitrary radial and angular indices propagating in the isotropic media. The propagation dynamics can be understood as a unitary transformation generated by a conserved quantity, where the rotation angle is exactly the intermodal Gouy phase of the spatiotemporal modes in the same order subspace. This spatiotemporal Gouy phase depends on the ellipticity of the wave packets and the group velocity dispersion (GVD) of the media. The phase, as a function of propagation distance, is categorized into three distinct regimes: normal dispersion, anomalous dispersion, and zero dispersion. Interestingly, in the regime of anomalous dispersion, the non-monotonic behavior induces to both distortion and revival of the intensity distribution, thereby establishing a phase-locked mechanism that is analogous to the Talbot effect.
format Preprint
id arxiv_https___arxiv_org_abs_2509_00295
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SU(2) symmetry of spatiotemporal Gaussian modes propagating in the isotropic dispersive media
Tang, Fangqing
Xiao, Xing
Chen, Lixiang
Optics
Quantum Physics
The far-field intensity distribution of spatiotemporal Laguerre-Gaussian (STLG) modes propagating in free space exhibits a multi-petal pattern analogous to that observed in tilted Hermite-Gaussian modes. Here, we show that this phenomenon can be explained by the SU(2) symmetry of spatiotemporal Gaussian modes, which can support the irreducible representation of SU(2) group and enable the construction of the spatiotemporal model Poincaré sphere. We have also derived analytical expressions for the STLG mode with an arbitrary radial and angular indices propagating in the isotropic media. The propagation dynamics can be understood as a unitary transformation generated by a conserved quantity, where the rotation angle is exactly the intermodal Gouy phase of the spatiotemporal modes in the same order subspace. This spatiotemporal Gouy phase depends on the ellipticity of the wave packets and the group velocity dispersion (GVD) of the media. The phase, as a function of propagation distance, is categorized into three distinct regimes: normal dispersion, anomalous dispersion, and zero dispersion. Interestingly, in the regime of anomalous dispersion, the non-monotonic behavior induces to both distortion and revival of the intensity distribution, thereby establishing a phase-locked mechanism that is analogous to the Talbot effect.
title SU(2) symmetry of spatiotemporal Gaussian modes propagating in the isotropic dispersive media
topic Optics
Quantum Physics
url https://arxiv.org/abs/2509.00295