Harvard John A. Paulson School of Engineering and Applied Sciences, 9 Oxford Street, Cambridge, Massachusetts 02138, USA.
Data Lab and Applied Physics, Vrije Universiteit Brussel, 1050 Brussel, Belgium.
Phys Rev Lett. 2023 May 5;130(18):183601. doi: 10.1103/PhysRevLett.130.183601.
Spin-orbit interactions in evanescent fields have recently attracted significant interest. In particular, the transfer of the Belinfante spin momentum perpendicular to the propagation direction generates polarization-dependent lateral forces on particles. However, it is still elusive as to how the polarization-dependent resonances of large particles synergize with the incident light's helicity and resultant lateral forces. Here, we investigate these polarization-dependent phenomena in a microfiber-microcavity system where whispering-gallery-mode resonances exist. This system allows for an intuitive understanding and unification of the polarization-dependent forces. Contrary to previous studies, the induced lateral forces at resonance are not proportional to the helicity of incident light. Instead, polarization-dependent coupling phases and resonance phases generate extra helicity contributions. We propose a generalized law for optical lateral forces and find the existence of optical lateral forces even when the helicity of incident light is zero. Our work provides new insights into these polarization-dependent phenomena and an opportunity to engineer polarization-controlled resonant optomechanical systems.
自旋轨道相互作用在消逝场中最近引起了人们的极大兴趣。特别是，与传播方向垂直的 Belinfante 自旋动量的转移会在粒子上产生偏振相关的横向力。然而，大粒子的偏振相关共振如何与入射光的螺旋度和产生的横向力协同作用，仍然难以捉摸。在这里，我们在存在 whispering-gallery-mode 共振的微光纤-微腔系统中研究了这些偏振相关现象。该系统允许直观地理解和统一偏振相关力。与以前的研究相反，在共振时诱导的横向力与入射光的螺旋度不成正比。相反，偏振相关的耦合相和共振相产生额外的螺旋贡献。我们提出了光学横向力的广义定律，并发现即使入射光的螺旋度为零，也存在光学横向力。我们的工作为这些偏振相关现象提供了新的见解，并为工程偏振控制的共振光机械系统提供了机会。
