Forces and torques exerted on dielectric disks trapped in a Gaussian standing wave are analyzed theoretically for disks of radius $2\mu \text{m}$ with indices of refraction $n=1.45$ and $n=2.0$ as well as disks of radius 200 nm with $n=1.45$. Calculations of the forces and torques were conducted both analytically and numerically using a discrete-dipole approximation method. Besides harmonic terms, third-order rotranslational coupling terms in the potential energy can be significant and a necessary consideration when describing the dynamics of disks outside of the Rayleigh limit. The coupling terms are a result of the finite extension of the disk coupling to both the Gaussian and standing-wave geometry of the beam. The resulting dynamics of the degrees of freedom most affected by the coupling terms exhibit several sidebands as evidenced in the power spectral densities. Simulations show that for Gaussian beam waists of $2–4\mu \text{m}$ the disk remains stably trapped.

中文翻译：

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高斯驻波中光悬浮介质盘的稳定性和动力学超出谐波近似

从理论上分析了半径为高的圆盘上在高斯驻波中捕获的介质圆盘上施加的力和转矩 $2\mu \text{米}$ 折射率 $ñ=1.45$ 和 $ñ=2.0$ 以及半径为200 nm的圆盘 $ñ=1.45$。力和扭矩的计算是使用离散偶极近似方法进行解析和数值计算的。除谐波项外，势能中的三阶旋转平移耦合项可能很重要，也是描述Rayleigh极限之外的磁盘动力学时的必要考虑因素。耦合项是圆盘耦合有限扩展到梁的高斯和驻波几何形状的结果。由耦合项影响最大的自由度动态结果显示出几个边带，如功率谱密度所示。仿真表明，对于高斯束腰$2–4\mu \text{米}$ 磁盘仍然稳定地被捕获。