Coupled surface polaritons and the Casimir force

First-order correction to the Casimir force within an inhomogeneous medium

For the Casimir piston filled with an inhomogeneous medium, the Casimir energy is regularized and expressed with cylinder kernel coefficients by using the first-order perturbation theory. When the refraction index of the medium is smoothly inhomogeneous (i.e., derivatives of all orders exist), logarithmically cutoff-dependent term in Casimir energy is found. We show that in the piston model this term vanishes in the force and thus the Casimir force is always cutoff-independent, but this term will remain in the force in the half-space model and must be removed by additional regularization. We i…

Designing evanescent optical interactions to control the expression of Casimir forces in optomechanical structures

We propose an optomechanical structure consisting of a photonic-crystal (holey) membrane suspended above a layered silicon-on-insulator substrate in which resonant bonding/antibonding optical forces created by externally incident light from above enable all-optical control and actuation of stiction effects induced by the Casimir force. In this way, one can control how the Casimir force is expressed in the mechanical dynamics of the membrane, not by changing the Casimir force directly but by optically modifying the geometry and counteracting the mechanical spring constant to bring the system in…

Transverse Chiral Optical Forces by Chiral Surface Plasmon Polaritons

Recently the new concepts of transverse spin angular momentum and Belinfante spin momentum of evanescent waves have drawn considerable attention. Here, we investigate these novel physical properties of electromagnetic fields in the context of locally excited surface plasmon polaritons. We demonstrate, both analytically and numerically, that locally excited surface plasmon polaritons possess transverse spin angular momentum and Belinfante momentum with rich and non-trivial characteristics. We also show that the transverse spin angular momentum of locally excited surface plasmon polaritons leads…

Creation of Van der Waals, Casimir, and many more stochastic forces, with light radiation pressure via optics of randomly fluctuating sources

The mechanical action on matter of the electromagnetic field emitted by a fluctuating source is governed by its statistics. In particular, thermal sources and vacuum fluctuations exert on bodies those well-known Casimir (C) and Van der Waals (VdW) forces. However, we have recently demonstrated that partially coherent random electromagnetic fields emitted by tailored optical sources, induce a photonic force on particles which, in particular, may be equivalent to those of Van der Waals and Casimir.

Corrected Proximity-Force Approximation for Lateral Casimir Forces

The widely-adopted proximity-force approximation (PFA) to estimate normal Casimir forces is known to be asymptotically exact at vanishing separations. In this letter, we propose a correction to the PFA, which is sufficiently accurate in predicting displacement-induced lateral Casimir forces between a sphere and a grating, for separation-to-radius ratio up to 0.5, far beyond the limit within which the application of PFA is previously restricted. Our result allows convenient estimation of Casimir interactions and thus shall be useful in relevant experimental and engineering Casimir applications.…

Optical trapping and critical Casimir forces

Critical Casimir forces emerge between objects, such as colloidal particles, whenever their surfaces spatially confine the fluctuations of the order parameter of a critical liquid used as a solvent. These forces act at short but microscopically large distances between these objects, reaching often hundreds of nanometers. Keeping colloids at such distances is a major experimental challenge, which can be addressed by the means of optical tweezers. Here, we review how optical tweezers have been successfully used to quantitatively study critical Casimir forces acting on particles in suspensions. A…

源自量子表面响应的纳米尺度卡西米尔力软化

Nanoscale Casimir Force Softening Originated from Quantum Surface Responses

本文提出三维共形映射方法研究表面电子对纳米尺度卡西米尔力的影响，发现表面电子可因材料和晶面不同而增强或抑制该力，并揭示其机制为卡西米尔力软化。

相互穿插的矩形光栅之间Casimir力的强几何依赖性

Strong geometry dependence of the Casimir force between interpenetrated rectangular gratings

本研究通过片上检测平台测量了相互穿插的矩形光栅间的Casimir力，发现其具有极强的几何依赖性，与近程力近似偏差达约500倍，且穿插后力变为非零且与位移无关，证明光栅可强烈调控纳米机械组件间的相互作用。