Controllable multi-trap optical tweezers based on low loss optical phase change and metalens
Authors: Wang Yan , Peng Miao , Cheng Wei , Peng Zheng , Cheng Hao , Zang Sheng-Yin , Liu Hao , Ren Xiao-Dong , Shuai Yu-Bei , Huang Cheng-Zhi , Wu Jia-Gui , Yang Jun-Bo ,   College of Artificial Intelligence, Southwest University, Chongqing 400715, China,   Center of Material Science, National University of Defense Technology, Changsha 410073, China,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China,   Key Laboratory of Luminescence Analysis and Molecular Sensing, Ministry of Education, School of Pharmaceutical, Southwest University, Chongqing 400715, China,   College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
Published: November 2022

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<sub>2</sub>S<sub>3</sub>. The horizontal and axial analysis of the optical force acting on two 250-nm-radius SiO<sub>2</sub> particles are also carried out. The simulation results show that when Sb<sub>2</sub>S<sub>3</sub> is in the crystalline state, the transverse optical trap stiffness <inline-formula><tex-math id="M5">\begin{document}$ {k}_{x} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M5.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M5.png"/></alternatives></inline-formula> of two particles reaches about 25.7 pN/(μm·W) and 37.4 pN/(μm·W), respectively, and the axial optical trap stiffness <inline-formula><tex-math id="M6">\begin{document}$ {k}_{z} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M6.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M6.png"/></alternatives></inline-formula> for each particle is about 10.0 pN/(μm·W). When the Sb<sub>2</sub>S<sub>3</sub> is in the amorphous state, both <inline-formula><tex-math id="M7">\begin{document}$ {k}_{x} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M7.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M7.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M8">\begin{document}$ {k}_{z} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M8.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="2-20221794_M8.png"/></alternatives></inline-formula> are about 1/10 of the counterpart of its crystalline state. As a result, the particle is not stably trapped in the <i>z</i>-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<sub>2</sub>S<sub>3</sub>, 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.