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High Trap Stiffness Microcylinders for Nanophotonic Trapping

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journal contribution
posted on 21.06.2019, 00:00 by Ryan P. Badman, Fan Ye, Wagma Caravan, Michelle D. Wang
Nanophotonic waveguides have enabled on-chip optical trap arrays for high-throughput manipulation and measurements. However, the realization of the full potential of these devices requires trapping enhancement for applications that need large trapping force. Here, we demonstrate a solution via fabrication of high refractive index cylindrical trapping particles. Using two different fabrication processes, a cleaving method and a novel lift-off method, we produced cylindrical silicon nitride (Si3N4) particles and characterized their trapping properties using the recently developed nanophotonic standing-wave array trap (nSWAT) platform. Relative to conventionally used polystyrene microspheres, the fabricated Si3N4 microcylinders attain an approximately 3- to 6-fold trap stiffness enhancement. Furthermore, both fabrication processes permit tunable microcylinder geometry, and the lift-off method also results in ultrasmooth surface termination of the ends of the microcylinders. These combined features make the Si3N4 microcylinders uniquely suited for a broad range of high-throughput, high-force, nanophotonic waveguide-based optical trapping applications.