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Optimization and visualization of phase modulation with filtered and amplified maximal-length sequence for SBS suppression in a short fiber system: a theoretical treatment

Optimization and visualization of phase modulation with filtered and amplified maximal-length sequence for SBS suppression in a short fiber system: a theoretical treatment
Optimization and visualization of phase modulation with filtered and amplified maximal-length sequence for SBS suppression in a short fiber system: a theoretical treatment
We use a model to investigate both the temporal and spectral characteristics of a signal lightwave which has been spectrally broadened through phase modulation with a maximal-length sequence (MLS), which is a common type of pseudo-random bit sequence. The enhancement of the stimulated Brillouin scattering (SBS) threshold of the modulated lightwave in a fiber system is evaluated by numerically simulating the coupled three-wave SBS interaction equations.
We find that SBS can build up on a nanosecond-level time scale in a short fiber, which can reduce the SBS suppressing capability of MLS modulation waveforms with GHz-level clock rate, if the sub-sequence ("run") lengths with the same symbol (zero or one) of the MLS extend over several nanoseconds. To ensure the SBS buildup is perturbed and thus suppressed also during these long sub-sequences, we introduce a low-pass filter to average the signal over several
bits so that the modulation waveform changes gradually even during long runs and amplify the RF modulation waveforms to the level required for sufficient spectral broadening and carrier suppression of the optical signal. We find that the SBS suppression depends non-monotonically on the parameters of the filtered and amplified MLS waveform such as pattern length, modulation
depth, and the ratio of low-pass filter cutoff frequency to clock rate for maximum SBS mitigation. We optimize the SBS suppression through numerical simulations and discuss it in terms of the temporal and spectral characteristics of the lightwave and modulation waveform using derived analytical expressions and numerical simulations. The simulations indicate that the normalized
SBS threshold reaches a maximum for a RMS modulation depth of 0.56π and a ratio of filter cutoff frequency to clock rate of 0.54 and that MLS9 is superior to other investigated patterns.
1094-4087
16781-16803
Yang, Yifeng
0efc6771-972c-402f-af4f-3468b2991b5c
Li, Binglin
eaf1c3d2-9c0a-4f00-a413-dc160e38d8c9
Liu, Meizhong
88209159-783c-4950-9347-eeae8f79c80f
Huang, Xuchen
8ee97a78-3d15-481d-9927-ec7af2a36478
Feng, Yutong
8257a816-5e4a-47bc-8aa2-e364c4d6e21e
Cheng, Dan
54bc64ff-0e21-44c7-a17f-ef91e7142b39
He, Bing
be7a2c34-6ba4-42fc-9351-47fd6e7ed9a9
Zhou, Jun
71a1fb00-0eaf-4a69-b073-7c876c04274e
Nilsson, Johan
f41d0948-4ca9-4b93-b44d-680ca0bf157b
Yang, Yifeng
0efc6771-972c-402f-af4f-3468b2991b5c
Li, Binglin
eaf1c3d2-9c0a-4f00-a413-dc160e38d8c9
Liu, Meizhong
88209159-783c-4950-9347-eeae8f79c80f
Huang, Xuchen
8ee97a78-3d15-481d-9927-ec7af2a36478
Feng, Yutong
8257a816-5e4a-47bc-8aa2-e364c4d6e21e
Cheng, Dan
54bc64ff-0e21-44c7-a17f-ef91e7142b39
He, Bing
be7a2c34-6ba4-42fc-9351-47fd6e7ed9a9
Zhou, Jun
71a1fb00-0eaf-4a69-b073-7c876c04274e
Nilsson, Johan
f41d0948-4ca9-4b93-b44d-680ca0bf157b

Yang, Yifeng, Li, Binglin, Liu, Meizhong, Huang, Xuchen, Feng, Yutong, Cheng, Dan, He, Bing, Zhou, Jun and Nilsson, Johan (2021) Optimization and visualization of phase modulation with filtered and amplified maximal-length sequence for SBS suppression in a short fiber system: a theoretical treatment. Optics Express, 29 (11), 16781-16803. (doi:10.1364/OE.426070).

Record type: Article

Abstract

We use a model to investigate both the temporal and spectral characteristics of a signal lightwave which has been spectrally broadened through phase modulation with a maximal-length sequence (MLS), which is a common type of pseudo-random bit sequence. The enhancement of the stimulated Brillouin scattering (SBS) threshold of the modulated lightwave in a fiber system is evaluated by numerically simulating the coupled three-wave SBS interaction equations.
We find that SBS can build up on a nanosecond-level time scale in a short fiber, which can reduce the SBS suppressing capability of MLS modulation waveforms with GHz-level clock rate, if the sub-sequence ("run") lengths with the same symbol (zero or one) of the MLS extend over several nanoseconds. To ensure the SBS buildup is perturbed and thus suppressed also during these long sub-sequences, we introduce a low-pass filter to average the signal over several
bits so that the modulation waveform changes gradually even during long runs and amplify the RF modulation waveforms to the level required for sufficient spectral broadening and carrier suppression of the optical signal. We find that the SBS suppression depends non-monotonically on the parameters of the filtered and amplified MLS waveform such as pattern length, modulation
depth, and the ratio of low-pass filter cutoff frequency to clock rate for maximum SBS mitigation. We optimize the SBS suppression through numerical simulations and discuss it in terms of the temporal and spectral characteristics of the lightwave and modulation waveform using derived analytical expressions and numerical simulations. The simulations indicate that the normalized
SBS threshold reaches a maximum for a RMS modulation depth of 0.56π and a ratio of filter cutoff frequency to clock rate of 0.54 and that MLS9 is superior to other investigated patterns.

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Optimization and visualization of phase modulation with filtered and amplified maximal-length sequence for SBS suppression in a short fiber system: a theoretical treatment - Accepted Manuscript
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Accepted/In Press date: 9 May 2021
e-pub ahead of print date: 14 May 2021
Published date: 14 May 2021
Additional Information: Funding. Youth Innovation Promotion Association of the Chinese Academy of Sciences (2020252); National Key Research and Development Program of China (2018YFB0504500); National Natural Science Foundation of China (61705243, 61735007, 61805261); Special Project for Research and Development in Key areas of Guangdong Province (2018B090904001); Air Force Office of Scientific Research (FA9550-17-1-0007).

Identifiers

Local EPrints ID: 449235
URI: http://eprints.soton.ac.uk/id/eprint/449235
ISSN: 1094-4087
PURE UUID: 85d9dc69-b48f-4669-afe7-426f4204b7aa
ORCID for Yutong Feng: ORCID iD orcid.org/0000-0002-6839-2106
ORCID for Johan Nilsson: ORCID iD orcid.org/0000-0003-1691-7959

Catalogue record

Date deposited: 20 May 2021 16:31
Last modified: 09 Jan 2022 02:57

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Contributors

Author: Yifeng Yang
Author: Binglin Li
Author: Meizhong Liu
Author: Xuchen Huang
Author: Yutong Feng ORCID iD
Author: Dan Cheng
Author: Bing He
Author: Jun Zhou
Author: Johan Nilsson ORCID iD

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