Inverse Design of Plasmonic Nanotweezers by Topology Optimization
Damian Nelson, Sejeong Kim, Kenneth B. Crozier
Abstract
We use topology optimization and adjoint sensitivity analysis to inversely design plasmonic nanoapertures for nanoparticle optical trapping. Surprisingly, our algorithm produces a central aperture in a gold film that is reminiscent of the well-known double nanohole. Next, we apply our technique to the region surrounding the central aperture and produce structures with nonintuitive features unavailable with forward design methods. These outer structures increase the electric field intensity in the central aperture, increasing the trapping potential by ∼4.97 times. Our new design produces a trapping potential that is ∼1.95 and ∼27.9 times greater than previous representative studies on algorithm-designed and forward-designed nanotweezers, respectively. Our work demonstrates that topology optimization is an effective method for the design of high-performance plasmonic nanotweezers.