Extended three dimensional optical tweezers with a Single Gaussian Beam in a stratified medium
Abstract
We demonstrate a simple and effective approach for realizing extended volumetric optical trapping using a single linearly polarized Gaussian beam propagating through a stratified medium with engineered refractive index gradients. On modifying the gradients, the focal field undergoes axial elongation and develops multiple localized intensity maxima, enabling simultaneous trapping of particles at distinct axial planes. Both on-axis and off-axis trapping configurations are experimentally observed, forming a volumetric particle distribution without the need for complex holographic beam shaping. A rigorous theoretical framework based on the Debye Wolf diffraction formalism combined with Generalized Lorenz-Mie Theory is employed to model the focused field and the resulting optical forces. The analysis, substantiated with numerical simulations, shows that spherical aberration arising from refractive-index discontinuities plays a crucial role in redistributing optical energy, leading to the formation of multiple stable trapping regions. The axial trapping potential decreases monotonically with increasing mismatch, indicating a trade-off between multi-site trapping capability and trapping potential, which is in quantitative agreement with experimental observations. This work establishes refractive index engineering as a powerful tool for tailoring three-dimensional optical force landscapes using minimal optical complexity, thus offering a scalable alternative to conventional holographic optical tweezers towards applications in colloidal assembly, micromanipulation, and biophotonics.
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BibTeX
@misc{das2026extended,
title = {{Extended three dimensional optical tweezers with a Single Gaussian Beam in a stratified medium}},
author = {Sramana Das and Suvajit Dey and Nirmalya Ghosh and Subhasish Dutta Gupta and Ayan Banerjee},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.23757},
eprint = {2609.23757},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.23757},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Extended three dimensional optical tweezers with a Single Gaussian Beam in a stratified medium
AU - Sramana Das
AU - Suvajit Dey
AU - Nirmalya Ghosh
AU - Subhasish Dutta Gupta
AU - Ayan Banerjee
PY - 2026
DA - 2026/09/20
PB - arXiv
DO - 10.48550/arxiv.2609.23757
UR - https://arxiv.org/abs/2609.23757
AB - We demonstrate a simple and effective approach for realizing extended volumetric optical trapping using a single linearly polarized Gaussian beam propagating through a stratified medium with engineered refractive index gradients. On modifying the gradients, the focal field undergoes axial elongation and develops multiple localized intensity maxima, enabling simultaneous trapping of particles at distinct axial planes. Both on-axis and off-axis trapping configurations are experimentally observed, forming a volumetric particle distribution without the need for complex holographic beam shaping. A rigorous theoretical framework based on the Debye Wolf diffraction formalism combined with Generalized Lorenz-Mie Theory is employed to model the focused field and the resulting optical forces. The analysis, substantiated with numerical simulations, shows that spherical aberration arising from refractive-index discontinuities plays a crucial role in redistributing optical energy, leading to the formation of multiple stable trapping regions. The axial trapping potential decreases monotonically with increasing mismatch, indicating a trade-off between multi-site trapping capability and trapping potential, which is in quantitative agreement with experimental observations. This work establishes refractive index engineering as a powerful tool for tailoring three-dimensional optical force landscapes using minimal optical complexity, thus offering a scalable alternative to conventional holographic optical tweezers towards applications in colloidal assembly, micromanipulation, and biophotonics.
ER -