Cao Zhenzhou, Qiu Xuejun, Hou Jin, Yang Chunyong
Opt Express. 2025 Jan 27;33(2):2376-2385. doi: 10.1364/OE.549782.
The Goos-Hänchen and Imbert-Fedorov shifts are significant wave phenomena, yet the underlying mechanism governing the spatiotemporal vortex pulses reflected and refracted on graphene remains opaque. In this study, we analytically derive the expressions for the centroid shifts of spatiotemporal vortex pulses by applying the Fresnel-Snell formulas to each plane wave in the incident spatiotemporal vortex pulse spectrum. We demonstrate that the longitudinal shifts are correlated with the angular shifts, and thus, both are subject to resonant enhancement in the vicinity of the Brewster angle. It is possible to tune the resonant enhancement of the shifts by modifying the Fermi energy of graphene. An increase in the vortex topological charge results in an enhancement of both the angular and longitudinal shifts while the transverse shifts are reduced. The shifts of the intensity distribution, in accordance with the Goos-Hänchen and Imbert-Fedorov shifts, facilitate experimental measurements. The high frequency in the terahertz region will diminish the resonant enhancement of the spatial shifts of the reflected wavepackets. The analysis presented here can be extended with minimal effort to spatiotemporal vortex pulses reflected and refracted on other two-dimensional atomic crystals.
古斯-汉欣位移和因伯特-费多罗夫位移是重要的波动现象，然而，关于时空涡旋脉冲在石墨烯上反射和折射的潜在机制仍不明确。在本研究中，我们通过将菲涅耳-斯涅尔公式应用于入射时空涡旋脉冲光谱中的每个平面波，解析推导了时空涡旋脉冲质心位移的表达式。我们证明纵向位移与角向位移相关，因此，两者在布儒斯特角附近都会受到共振增强。通过改变石墨烯的费米能量，可以调节位移的共振增强。涡旋拓扑电荷的增加会导致角向和纵向位移都增强，而横向位移则减小。强度分布的位移，与古斯-汉欣位移和因伯特-费多罗夫位移一致，便于进行实验测量。太赫兹区域的高频将减弱反射波包空间位移的共振增强。此处给出的分析可以很容易地扩展到在其他二维原子晶体上反射和折射的时空涡旋脉冲。
