Comparison of plasmonic structures in terms of temperature increase under equivalent maximal trapping forces

Yong-Jun Yang and Yong-Gu Lee

Plasmonic optical trapping is a new approach that can potentially overcome some of the limitations associated with conventional optical trapping. Plasmonic tweezers generate heat because of the absorption of light at the surface of metals, and this is one of the contributions to the failure of stable trapping. Heating problems and the trapping forces tend to differ with the geometry of the plasmonicstructures. Nanodisk structures can generally deliver stronger trapping forces than nanohole structures. However, the nanodisk structures also lead to greater heat generation, which can cause the medium to boil and eventually produce bubbles that can potentially push trapped particles away from the trap. Concentrated local heat can also melt the plasmonic features or instantaneously vaporize the medium. In this paper, we have closely examined this heat generation problem for two typical plasmonicstructures, nanodisks and nanoholes, and provided a detailed analysis. For identical force generations, it is shown that the nanohole structures exhibit less heat generation.

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