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Optimization of phase modulation formats for suppression of stimulated Brillouin scattering in optical fibers

Optimization of phase modulation formats for suppression of stimulated Brillouin scattering in optical fibers
Optimization of phase modulation formats for suppression of stimulated Brillouin scattering in optical fibers
We theoretically investigate nonlinear optimization of periodic phase modulation for suppression of stimulated Brillouin scattering (SBS) in single-mode optical fibers. We use nonlinear multi-parameter Pareto optimization to find modulations that represent the best trade-off between SBS and optical linewidth, as measured by its RMS value. The optimization uses a temporal-amplitude-domain finite-difference Brillouin solver with noise initiation to find the best phase modulation patterns in the presence of coherent so-called cross-interactions. These can be important in short fibers, when the period is large enough to make the frequency-domain separation of the modulated signal comparable to, or smaller than, the Brillouin gain linewidth. We calculate the SBS threshold for the optimized modulation patterns and find that smaller spectral line-spacing improves the SBS threshold for the same linewidth. By contrast, whereas the maximum modulation depth and modulation frequency influences the range of accessible linewidths, they do not significantly alter the threshold for a given linewidth. We investigate the dependence on fiber length and find that while shorter fibers have a higher threshold, the increase is smaller than the often-assumed inverse dependence on length. Furthermore, we find that optimized formats are superior in terms of SBS threshold as well as in terms of linewidth control, compared to random modulation.
Nonlinear optics , Stimulated Brillouin scattering, Optical fiber amplifiers
0018-9197
Achar Vasant, Harish
833a8dce-cb98-479c-a78d-f754883ff2fd
Nilsson, Johan
f41d0948-4ca9-4b93-b44d-680ca0bf157b
Achar Vasant, Harish and Nilsson, Johan (2017) Optimization of phase modulation formats for suppression of stimulated Brillouin scattering in optical fibers IEEE Journal of Quantum Electronics

Achar Vasant, Harish and Nilsson, Johan (2017) Optimization of phase modulation formats for suppression of stimulated Brillouin scattering in optical fibers IEEE Journal of Quantum Electronics

Record type: Article

Abstract

We theoretically investigate nonlinear optimization of periodic phase modulation for suppression of stimulated Brillouin scattering (SBS) in single-mode optical fibers. We use nonlinear multi-parameter Pareto optimization to find modulations that represent the best trade-off between SBS and optical linewidth, as measured by its RMS value. The optimization uses a temporal-amplitude-domain finite-difference Brillouin solver with noise initiation to find the best phase modulation patterns in the presence of coherent so-called cross-interactions. These can be important in short fibers, when the period is large enough to make the frequency-domain separation of the modulated signal comparable to, or smaller than, the Brillouin gain linewidth. We calculate the SBS threshold for the optimized modulation patterns and find that smaller spectral line-spacing improves the SBS threshold for the same linewidth. By contrast, whereas the maximum modulation depth and modulation frequency influences the range of accessible linewidths, they do not significantly alter the threshold for a given linewidth. We investigate the dependence on fiber length and find that while shorter fibers have a higher threshold, the increase is smaller than the often-assumed inverse dependence on length. Furthermore, we find that optimized formats are superior in terms of SBS threshold as well as in terms of linewidth control, compared to random modulation.

Text FINAL VERSION - Accepted Manuscript
Restricted to Repository staff only until 7 December 2017.

More information

Accepted/In Press date: 7 September 2017
Keywords: Nonlinear optics , Stimulated Brillouin scattering, Optical fiber amplifiers

Identifiers

Local EPrints ID: 413980
URI: http://eprints.soton.ac.uk/id/eprint/413980
ISSN: 0018-9197
PURE UUID: e9fe8f21-a7e6-46cc-8d5b-8ef996546943
ORCID for Johan Nilsson: ORCID iD orcid.org/0000-0003-1691-7959

Catalogue record

Date deposited: 12 Sep 2017 16:31
Last modified: 02 Nov 2017 17:30

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Contributors

Author: Harish Achar Vasant
Author: Johan Nilsson ORCID iD

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