Visualizing colloidal aggregation with femtosecond optical tweezers

Debabrata Goswami

doi:10.1117/12.2528518

9 September 2019 Visualizing colloidal aggregation with femtosecond optical tweezers

Debabrata Goswami

Proceedings Volume 11083, Optical Trapping and Optical Micromanipulation XVI; 110832C (2019) https://doi.org/10.1117/12.2528518
Event: SPIE Nanoscience + Engineering, 2019, San Diego, California, United States

Abstract

Optical tweezers manipulate microscopic objects using forces arising from the subtle interplay of optical scattering and gradient forces of highly focused laser beams. Unlike conventional backscatter signal for optical tweezers, the twophoton fluorescence (TPF) trapping signal from femtosecond optical tweezers (FOTs) shows a slow counterintuitive decay, when the trapped particles are not entirely within the laser-illuminated volume. A change in the corner frequency of FOT is also noted with the TPF technique. These observations are evident even at low average powers. The high peak powers trap not only single microspheres but also encourage optically directed self-assembly. We use TPF signatures of trapped particles to show the existence of a directed self-assembly process and elucidate the structural dynamics during the process of cluster formation.

Conference Presentation

Citation Download Citation

Debabrata Goswami "Visualizing colloidal aggregation with femtosecond optical tweezers", Proc. SPIE 11083, Optical Trapping and Optical Micromanipulation XVI, 110832C (9 September 2019); https://doi.org/10.1117/12.2528518

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