Inverse design of plasmonic nanotweezers

Plasmonic apertures concentrate optical fields, enhancing the gradient force for precise trapping of nanoscale entities. Traditionally, design relied on intuition and simulations. We instead present a novel approach using topology optimization and adjoint sensitivity analysis. Our computational algorithm inversely designs plasmonic nanoapertures. Surprisingly, the algorithm produces an aperture reminiscent of the double nanohole, a structure that has been adopted by many groups. Our algorithm produces outer structures that surround the aperture and enhance the electric field intensity, increasing trapping potential by ~4.97 times. Compared to representative studies, our design achieves ~1.95 and ~27.9 times greater trapping potential than algorithm-designed and forward-designed nanotweezers, respectively. This work establishes topology optimization as an effective method for high-performance plasmonic nanotweezer design.