基于低损光学相变和超透镜的可控多阱光镊

Controllable multi-trap optical tweezers based on low loss optical phase change and metalens

为提升光镊在三维空间中对粒子的捕获性能,本文设计和分析了新型的双阱和多阱超透镜光镊方案.首先基于低损耗相变材料Sb_(2)S_(3)设计了可控超透镜双阱光镊,并对两个半径为250 mm的SiO_(2)粒子所受光力进行了矢量横向分析和轴向分析.仿真实验结果表明,当Sb_(2)S_(3)在晶态下时,超透镜捕获的两个粒子的横向光阱刚度k_(x)分别达到了约25.7 pN/(μm·W)和37.4 pN/(μm·W),轴向光阱刚度k_(z)均约为10.0 pN/(μm·W);而当Sb_(2)S_(3)在非晶态下时,k_(x)和k_(z)值均降低到其对应晶态下的1/10,且此时粒子在z方向上不能被稳定捕获,从而实现了在三维空间中对粒子的可控捕获.进一步本文给出了阵列式的可控多阱光镊.通过调控相变材料Sb_(2)S_(3)的晶态和非晶态,能形成不同组合粒子的三维捕获方案.这些新型可控光镊可实现多种方式的三维空间粒子捕获,提高了光镊的灵活性,为超透镜在光镊领域中的应用提供了一种新思路.

Novel dual-trap and multi-trap optical tweezers are designed and analyzed,in order to enhance the particle trapping performance of optical tweezers in three-dimensional(3D)space.Firstly,controllable dual-trap optical tweezers are proposed based on metalens and the low-loss optical phase-change material Sb_(2)S_(3).The horizontal and axial analysis of the optical force acting on two 250-nm-radius SiO_(2)particles are also carried out.The simulation results show that when Sb_(2)S_(3)is in the crystalline state,the transverse optical trap stiffness k_(x)of two particles reaches about 25.7 pN/(μm·W)and 37.4 pN/(μm·W),respectively,and the axial optical trap stiffness k_(z)for each particle is about 10.0 pN/(μm·W).When the Sb_(2)S_(3)is in the amorphous state,both k_(x)and k_(z)are about 1/10 of the counterpart of its crystalline state.As a result,the particle is not stably trapped in the z-direction,and thus enabling the controllability of trapping particles in 3D space.Furthermore,array-type multi-trap optical tweezers are proposed.By regulating the crystal state and noncrystal state of phase-change material Sb_(2)S_(3),it is convenient to form different combinations of 3D trap schemes.These new optical tweezers can realize 3D space particle trap in various ways,thereby improving the flexibility of optical tweezers,and providing a series of new ways of implementing the metalens-based optical tweezers.