Laser writing of parabolic micromirrors with a high numerical aperture for optical trapping and rotation
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On-chip optical trapping systems allow for high scalability and lower the barrier to access. Systems capable of trapping multiple particles typically come with high cost and complexity. Here, we present a technique for making parabolic mirrors with micrometer-size dimensions and high numerical apertures (NA > 1). Over 350 mirrors are made by simple CO2 laser ablation of glass followed by gold deposition. We fabricate mirrors of arbitrary diameter and depth at a high throughput rate by carefully controlling the ablation parameters. We use the micromirrors for three-dimensional optical trapping of microbeads in solution, achieving a maximum optical trap stiffness of 52 pN/μm/W. We, then, further demonstrate the viability of the mirrors as in situ optical elements through the rotation of a vaterite particle using reflected circularly polarized light. The method used allows for rapid and highly customizable fabrication of dense optical arrays.
Plaskocinski , T , Arita , Y , Bruce , G D , Persheyev , S , Dholakia , K , Di Falco , A & Ohadi , H 2023 , ' Laser writing of parabolic micromirrors with a high numerical aperture for optical trapping and rotation ' , Applied Physics Letters , vol. 123 , no. 8 , 081106 . https://doi.org/10.1063/5.0155512
Applied Physics Letters
Copyright © 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
DescriptionFunding: This work was supported by the UK Engineering and Physical Sciences Research Council (EP/P030017/1 and EP/S014403/1), by the European Research Council (ERC) under the European Union Horizon 2020 Research and Innovation Program (Grant Agreement No. 819346). HO acknowledges support from the Carnegie Trust for Universities of Scotland (Grant No. RIG007685). KD acknowledges support from the Australian Research Council (Grant No. DP220102303).
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