Spatial mode conversion of single photons at the C-band using in fiber long-period gratings

Abstract The ability to convert the spatial mode of single photons opens up a promising path to enhancing quantum communication protocols by enabling high-dimensional encoding and efficient multiplexing. In this work, we demonstrate spatial mode conversion of single photons at 1550.6 nm using a fibe...

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Main Authors: Rodrigo Amorim, Lars Grüner-Nielsen, Karsten Rottwitt
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-025-92394-x
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author Rodrigo Amorim
Lars Grüner-Nielsen
Karsten Rottwitt
author_facet Rodrigo Amorim
Lars Grüner-Nielsen
Karsten Rottwitt
author_sort Rodrigo Amorim
collection DOAJ
description Abstract The ability to convert the spatial mode of single photons opens up a promising path to enhancing quantum communication protocols by enabling high-dimensional encoding and efficient multiplexing. In this work, we demonstrate spatial mode conversion of single photons at 1550.6 nm using a fiber long-period grating (LPG). The fundamental $$\hbox {LP}_{01}$$ mode was converted to higher-order modes $$\hbox {LP}_{11}$$ and $$\hbox {LP}_{02}$$ , with quantum mode conversion efficiencies of 87.5 ± 1.4% and 96.1 ± 1.6%, respectively. The characterization of the converted single photons was carried out using a time-of-flight technique and coincidence measurements, by taking advantage of the differences in group velocity between the modes. We also performed loss measurements at the single-photon level and demonstrated mode re-conversion by using a second LPG to restore the photons back to the fundamental mode. These results highlight the potential of LPGs as a versatile tool for spatial mode manipulation at the single-photon level, with applications in high-dimensional quantum communication and nonlinear optical interactions.
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spelling doaj-art-5b3d73e90eb740cd97055fe74ff07b6b2025-08-20T01:57:44ZengNature PortfolioScientific Reports2045-23222025-03-011511910.1038/s41598-025-92394-xSpatial mode conversion of single photons at the C-band using in fiber long-period gratingsRodrigo Amorim0Lars Grüner-Nielsen1Karsten Rottwitt2Department of Electrical and Photonic Engineering, Technical University of DenmarkDepartment of Electrical and Photonic Engineering, Technical University of DenmarkDepartment of Electrical and Photonic Engineering, Technical University of DenmarkAbstract The ability to convert the spatial mode of single photons opens up a promising path to enhancing quantum communication protocols by enabling high-dimensional encoding and efficient multiplexing. In this work, we demonstrate spatial mode conversion of single photons at 1550.6 nm using a fiber long-period grating (LPG). The fundamental $$\hbox {LP}_{01}$$ mode was converted to higher-order modes $$\hbox {LP}_{11}$$ and $$\hbox {LP}_{02}$$ , with quantum mode conversion efficiencies of 87.5 ± 1.4% and 96.1 ± 1.6%, respectively. The characterization of the converted single photons was carried out using a time-of-flight technique and coincidence measurements, by taking advantage of the differences in group velocity between the modes. We also performed loss measurements at the single-photon level and demonstrated mode re-conversion by using a second LPG to restore the photons back to the fundamental mode. These results highlight the potential of LPGs as a versatile tool for spatial mode manipulation at the single-photon level, with applications in high-dimensional quantum communication and nonlinear optical interactions.https://doi.org/10.1038/s41598-025-92394-x
spellingShingle Rodrigo Amorim
Lars Grüner-Nielsen
Karsten Rottwitt
Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
Scientific Reports
title Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
title_full Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
title_fullStr Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
title_full_unstemmed Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
title_short Spatial mode conversion of single photons at the C-band using in fiber long-period gratings
title_sort spatial mode conversion of single photons at the c band using in fiber long period gratings
url https://doi.org/10.1038/s41598-025-92394-x
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AT larsgrunernielsen spatialmodeconversionofsinglephotonsatthecbandusinginfiberlongperiodgratings
AT karstenrottwitt spatialmodeconversionofsinglephotonsatthecbandusinginfiberlongperiodgratings