[20p-A202-1~19] 3.1 Basic optics and frontier of optics (merged with formerly 3.2 Equipment optics and materials)

▲ [20p-A202-4] Guiding the Expanding Direction of Optically Evolved Swarming of Gold Nanoparticles by Lithographically Fabricated Gold Nanodisks

〇(D)Chih-Hao Huang¹, Ya-Chiao Lee¹, Teruki Sugiyama¹, Tetsuhiro Kudo², Xu Shi³, Kosei Ueno³, Hiroaki Misawa^1,3, Hiroshi Masuhara¹ (1.National Yang Ming Chiao Tung Univ., Taiwan, 2.Toyota Tech. Inst., 3.Hokkaido Univ.)

Keywords:optical trapping, gold nanoparticles, electron beam lithography

Our group is studying the optical trapping of colloidal particles at air/solution and glass/solution interfaces, where the assemblies grow much larger than the irradiated area. In the case of metallic nanoparticles, a dumbbell-shaped assembly consisting of two swarms of fluctuating gold nanoparticles was observed at the glass/solution interface with a linearly polarized laser. In this work, we design the gold nanodisks according to the initial periodical alignment of gold nanoparticles and fabricate them on the glass substrate using electron beam lithography. When the trapping laser is focused at the center of the five fabricated nanodisks, a symmetric swarming assembly is observed. Interestingly, when the focus is shifted to the edge of the five nanodisks, the gold nanoparticle swarm at the right side quickly migrates to the left side, giving a uni-directional swarming. This is the first demonstration to control the swarming morphology outside the focal spot by using artificially fabricated nanostructures.