Phase-locked beam splitting with continuously tunable intensity ratio using stochastic phase masks
Abstract
We introduce a common-path beam splitter based on a randomly partitioned phase mask displayed on a spatial light modulator (SLM). The SLM aperture is divided into square patches, each randomly assigned to one of three phase ramps that steer light to three independent foci: two phase-locked beams and a dump that takes up the surplus power. We observe the beams in the focal plane of a lens. The fractions of patches assigned to each ramp set the focal intensities, with the focus positions controlled by the ramp slopes.We first demonstrate experimentally that the intensity ratio between the two foci can be tuned from 0 to 1 without distorting either of the spatial modes, and with their relative phase constant to within a few tens of mrad. We then derive a closed-form expression for the ensemble-averaged focal intensity, which decomposes into coherent foci of the desired pattern and a speckle background whose shape and amplitude are set by the patch size. The model is validated against experiment and against numerical Fraunhofer propagation, with quantitative agreement over about three orders of magnitude in intensity. We also identify the patch size as the central design parameter and characterize its experimental bounds.
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BibTeX
@misc{redon2026phaselocked,
title = {{Phase-locked beam splitting with continuously tunable intensity ratio using stochastic phase masks}},
author = {Melvin Redon and Titouan Gadeyne and Gaspard Beaufort and Saga Westerberg and Vartika Vishnoi and Peter Smorenburg and Anne-Lise Viotti and Thierry Ruchon and Cord L. Arnold},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02755},
eprint = {2611.02755},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02755},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Phase-locked beam splitting with continuously tunable intensity ratio using stochastic phase masks
AU - Melvin Redon
AU - Titouan Gadeyne
AU - Gaspard Beaufort
AU - Saga Westerberg
AU - Vartika Vishnoi
AU - Peter Smorenburg
AU - Anne-Lise Viotti
AU - Thierry Ruchon
AU - Cord L. Arnold
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02755
UR - https://arxiv.org/abs/2611.02755
AB - We introduce a common-path beam splitter based on a randomly partitioned phase mask displayed on a spatial light modulator (SLM). The SLM aperture is divided into square patches, each randomly assigned to one of three phase ramps that steer light to three independent foci: two phase-locked beams and a dump that takes up the surplus power. We observe the beams in the focal plane of a lens. The fractions of patches assigned to each ramp set the focal intensities, with the focus positions controlled by the ramp slopes.We first demonstrate experimentally that the intensity ratio between the two foci can be tuned from 0 to 1 without distorting either of the spatial modes, and with their relative phase constant to within a few tens of mrad. We then derive a closed-form expression for the ensemble-averaged focal intensity, which decomposes into coherent foci of the desired pattern and a speckle background whose shape and amplitude are set by the patch size. The model is validated against experiment and against numerical Fraunhofer propagation, with quantitative agreement over about three orders of magnitude in intensity. We also identify the patch size as the central design parameter and characterize its experimental bounds.
ER -