Inline inter-core phase control in multi-core fiber with a commercial polarization controller
Abstract
Inter-core phase control is a prerequisite for interferometry in multi-core fiber (MCF), but no compact inline element for this purpose is presently available, and existing approaches require fanout to single-mode fiber or free-space optics. We show that a commercial inline polarization controller, a low-loss and widely available component, can be operated as an inline inter-core phase shifter. Two-core interferometry on a jacketed four-core patchcord gives a reversible inter-core phase of 0.95 ± 0.02~rad from a single device, with an operating-point-independent lower bound of $0.38$~rad, driven through repeated load-unload cycles at a rate set by the actuator. A diametrically compressed disk model is used to predict the operating condition: with the input polarization aligned to a principal stress axis the device imparts a relative phase between cores without rotating the polarization state of either, which we verify by polarimetry on all four cores. The response is polarization dependent, falling to less than $0.58$~rad for the orthogonal input. The result is a practical, inline route to inter-core phase control and stabilization in all-MCF interferometers, requiring neither fanout to single-mode fiber nor free-space optics.
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BibTeX
@misc{contreras2026inline,
title = {{Inline inter-core phase control in multi-core fiber with a commercial polarization controller}},
author = {A. Contreras and A Muñoz and G. dos Santos and G. Cañas and G. Saavedra and C. Hermann-Avigliano and E. S. Gómez and G. Lima and S. P. Walborn},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03304},
eprint = {2611.03304},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03304},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Inline inter-core phase control in multi-core fiber with a commercial polarization controller
AU - A. Contreras
AU - A Muñoz
AU - G. dos Santos
AU - G. Cañas
AU - G. Saavedra
AU - C. Hermann-Avigliano
AU - E. S. Gómez
AU - G. Lima
AU - S. P. Walborn
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03304
UR - https://arxiv.org/abs/2611.03304
AB - Inter-core phase control is a prerequisite for interferometry in multi-core fiber (MCF), but no compact inline element for this purpose is presently available, and existing approaches require fanout to single-mode fiber or free-space optics. We show that a commercial inline polarization controller, a low-loss and widely available component, can be operated as an inline inter-core phase shifter. Two-core interferometry on a jacketed four-core patchcord gives a reversible inter-core phase of 0.95 ± 0.02~rad from a single device, with an operating-point-independent lower bound of $0.38$~rad, driven through repeated load-unload cycles at a rate set by the actuator. A diametrically compressed disk model is used to predict the operating condition: with the input polarization aligned to a principal stress axis the device imparts a relative phase between cores without rotating the polarization state of either, which we verify by polarimetry on all four cores. The response is polarization dependent, falling to less than $0.58$~rad for the orthogonal input. The result is a practical, inline route to inter-core phase control and stabilization in all-MCF interferometers, requiring neither fanout to single-mode fiber nor free-space optics.
ER -