The effect of the gain dependency of the linewidth of Brillouin amplification on double slope-assisted dynamic sensing techniques

Motil, Avi; Hadar, Raanan; Sovran, Ido; Tur, Moshe

doi:10.1117/12.2194744

Cited by 3 publications

(2 citation statements)

References 9 publications

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“…4 This unexpected finding means that BFS measurement error can appear in techniques such as the slope-assisted BOTDA that rely on the shape of the BGS. 5 We have recently proposed a dynamic BOTDA sensor tolerant to Brillouin gain changes in the sensing fiber. 3 This technique is based on the measurement of the phase-shift spectra of the RF signal that results from the coherent detection of a phase-modulated probe wave.…”

Section: Introductionmentioning

confidence: 99%

Gain dependence of measured spectra in coherent Brillouin optical time-domain analysis sensors

2016

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We report on the effects of large pump pulse powers on Brillouin optical time-domain analysis (BOTDA) sensors based on phase-modulated probe wave and coherent detection. It is found that the large Brillouin gain that comes from the use of high power pulses induces a narrowing of the RF phase-shift spectrum that is measured in these sensors. This narrowing leads to a Brillouin frequency shift measurement error when the sensor is configured for dynamic measurements. However, the effect has been found to be less significant than that observed in dynamic slope-assisted BOTDA sensors based on amplitude.

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Section: Introductionmentioning

confidence: 99%

Gain dependence of measured spectra in coherent Brillouin optical time-domain analysis sensors

2016

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“…However, recently, a previously unknown effect in stimulated Brillouin scattering (SBS) interaction has been discovered, by which the linewidth of the BGS has been found to depend on the pump pulse power [7], [8]. This unexpected finding means that BFS measurement errors can appear in techniques such as the slope-assisted BOTDA that rely on the shape of the BGS [9]. This effect is just signifcant in short fibers, where nonlinear effects are negligible and thus, high power pulses can be deployed.…”

Section: Introductionmentioning

confidence: 99%

Gain Dependence of the Phase-Shift Spectra Measured in Coherent Brillouin Optical Time-Domain Analysis Sensors

Mariñelarena

Urricelqui

Loayssa

2016

J. Lightwave Technol.

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We report on the effects of large pump pulse powers on Brillouin optical time-domain analysis (BOTDA) sensors based on phase-modulated probe wave and coherent self-heterodyne detection. These sensors are particularly suitable to perform dynamic strain and temperature measurements because the RF signal that is obtained when the probe wave is detected has a phase-shift spectrum that is independent to first order of the Brillouin gain. Therefore, a fixed optical frequency separation between pump and probe wave can be deployed and use the stable RF phase-shift spectrum to obtain the Brillouin frequency shift (BFS) from measured changes in the probe RF phase-shift. However, in this work, it is found that there is a narrowing of the RF phase-shift spectrum that depends on the Brillouin gain. This effect becomes significant when very high power pulses are used and the resultant large gain induces a narrowing of the RF phase-shift spectrum. This narrowing leads to a BFS measurement error when the sensor is configured for dynamic measurements. We analyze, theoretically and experimentally, the origins and the magnitude of the narrowing of RF phase-shift spectra for high pump pulses in a coherent BOTDA sensor. Furthermore, this spectral shape change is compared to the broadening of the gain spectrum that has been recently discovered in conventional direct-detection BOTDA sensors, which is linearly dependent on the pulse peak power injected to the fiber, finding that the spectral shape change is less significant in coherent BOTDA sensors. Finally, we quantify the BFS measurement error that it can induce and find the trade-offs to keep it below a certain threshold. It is found that, from a practical point of view, this effect is significant for short fibers, where nonlinear effects are negligible and large pump pulses can be used.

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[INVITED] State of the art of Brillouin fiber-optic distributed sensing

Motil

Bergman

Tur

2016

Optics & Laser Technology

330

165

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The effect of the gain dependency of the linewidth of Brillouin amplification on double slope-assisted dynamic sensing techniques

Cited by 3 publications

References 9 publications

Gain dependence of measured spectra in coherent Brillouin optical time-domain analysis sensors

Gain dependence of measured spectra in coherent Brillouin optical time-domain analysis sensors

Gain Dependence of the Phase-Shift Spectra Measured in Coherent Brillouin Optical Time-Domain Analysis Sensors

[INVITED] State of the art of Brillouin fiber-optic distributed sensing

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