Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves

Stimulated Brillouin scattering is a well-known nonlinear optical interaction valued for applications including narrow-linewidth lasers, phase conjugation, sensing, and RF-signal processing such as delay lines and filters. While interaction strength and linewidth directly affect device performance,...

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Main Authors: Wendao Xu, Maxime Zerbib, Arjun Iyer, Kien Phan Huy, Jean-Charles Beugnot, William H. Renninger
Format: Article
Language:English
Published: AIP Publishing LLC 2025-01-01
Series:APL Photonics
Online Access:http://dx.doi.org/10.1063/5.0242703
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author Wendao Xu
Maxime Zerbib
Arjun Iyer
Kien Phan Huy
Jean-Charles Beugnot
William H. Renninger
author_facet Wendao Xu
Maxime Zerbib
Arjun Iyer
Kien Phan Huy
Jean-Charles Beugnot
William H. Renninger
author_sort Wendao Xu
collection DOAJ
description Stimulated Brillouin scattering is a well-known nonlinear optical interaction valued for applications including narrow-linewidth lasers, phase conjugation, sensing, and RF-signal processing such as delay lines and filters. While interaction strength and linewidth directly affect device performance, most strongly interacting Brillouin systems have linewidths of many MHz, limited by the high frequency of the participating acoustic waves. By engineering Forward Inter-Modal Brillouin interactions to access the Fundamental Acoustic Modes (FIM-FAM), strong Brillouin coupling can be extended over a wide frequency range, including lower frequencies that support significantly narrower linewidths. In this work, sub-MHz Brillouin linewidths as narrow as 110 kHz are observed in tapered optical fibers with homogeneous waists. Tight confinement of both the optical and acoustic waves yields Brillouin gains over a thousand times higher than traditional backward Brillouin scattering in standard fibers, and a long waist and low-loss transitions enable a Brillouin interaction strength nearly a hundred times greater than prior taper-based FIM-FAM demonstrations. A specific radius and comprehensive polarization control suppress background scattering by over 40 dB relative to the signal. A comprehensive theoretical model is developed accounting for the dynamical behavior of optical and acoustic waves, reproducing qualitative behavior for several experimental configurations. In addition, the dependence of homogeneity of the linewidth is investigated and reveals a route toward further linewidth reduction by controlling phase-matched frequency variations throughout the waist. Extending strongly coupled Brillouin interactions to ultranarrow linewidths with a recipe for fabrication, detailed characterization techniques, and a comprehensive theoretical treatment will benefit high-performance Brillouin-based photonic applications.
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spelling doaj-art-086bb6c04c1e4c3cb9caa8091e2af44f2025-02-03T16:36:22ZengAIP Publishing LLCAPL Photonics2378-09672025-01-01101016108016108-1110.1063/5.0242703Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic wavesWendao Xu0Maxime Zerbib1Arjun Iyer2Kien Phan Huy3Jean-Charles Beugnot4William H. Renninger5Institute of Optics, University of Rochester, Rochester, New York 14627, USAInstitut FEMTO-ST, CNRS UMR 6174, Université Bourgogne Franche-Comté, Besançon 25000, FranceInstitute of Optics, University of Rochester, Rochester, New York 14627, USAInstitut FEMTO-ST, CNRS UMR 6174, Université Bourgogne Franche-Comté, Besançon 25000, FranceInstitut FEMTO-ST, CNRS UMR 6174, Université Bourgogne Franche-Comté, Besançon 25000, FranceInstitute of Optics, University of Rochester, Rochester, New York 14627, USAStimulated Brillouin scattering is a well-known nonlinear optical interaction valued for applications including narrow-linewidth lasers, phase conjugation, sensing, and RF-signal processing such as delay lines and filters. While interaction strength and linewidth directly affect device performance, most strongly interacting Brillouin systems have linewidths of many MHz, limited by the high frequency of the participating acoustic waves. By engineering Forward Inter-Modal Brillouin interactions to access the Fundamental Acoustic Modes (FIM-FAM), strong Brillouin coupling can be extended over a wide frequency range, including lower frequencies that support significantly narrower linewidths. In this work, sub-MHz Brillouin linewidths as narrow as 110 kHz are observed in tapered optical fibers with homogeneous waists. Tight confinement of both the optical and acoustic waves yields Brillouin gains over a thousand times higher than traditional backward Brillouin scattering in standard fibers, and a long waist and low-loss transitions enable a Brillouin interaction strength nearly a hundred times greater than prior taper-based FIM-FAM demonstrations. A specific radius and comprehensive polarization control suppress background scattering by over 40 dB relative to the signal. A comprehensive theoretical model is developed accounting for the dynamical behavior of optical and acoustic waves, reproducing qualitative behavior for several experimental configurations. In addition, the dependence of homogeneity of the linewidth is investigated and reveals a route toward further linewidth reduction by controlling phase-matched frequency variations throughout the waist. Extending strongly coupled Brillouin interactions to ultranarrow linewidths with a recipe for fabrication, detailed characterization techniques, and a comprehensive theoretical treatment will benefit high-performance Brillouin-based photonic applications.http://dx.doi.org/10.1063/5.0242703
spellingShingle Wendao Xu
Maxime Zerbib
Arjun Iyer
Kien Phan Huy
Jean-Charles Beugnot
William H. Renninger
Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
APL Photonics
title Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
title_full Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
title_fullStr Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
title_full_unstemmed Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
title_short Ultranarrow-linewidth stimulated Brillouin scattering with fundamental acoustic waves
title_sort ultranarrow linewidth stimulated brillouin scattering with fundamental acoustic waves
url http://dx.doi.org/10.1063/5.0242703
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