Investigation on sensitivity enhancement for optical fiber speckle sensors

Although experimental advances in the implementation and characterization of fiber speckle sensor have been reported, a suitable model to interpret the speckle-pattern variation under perturbation is desirable but very challenging to be developed due to the various factors influencing the speckle pattern. In this work, a new methodology based on the finite element method (FEM) for modeling and optimizing fiber specklegram sensors (FSSs) is proposed. The numerical method allows computational visualization and quantification, in near field, of changes of a step multi-mode fiber (SMMF) specklegram, due to the application of a uniformly distributed force line (UDFL). In turn, the local modifications of the fiber speckle produce changes in the optical power captured by a step single-mode fiber (SSMF) located just at the output end of the SMMF, causing a filtering effect that explains the operation of the FSSs. For each external force, the stress distribution and the propagations modes supported by the SMMF are calculated numerically by means of FEM. Then, those modes are vectorially superposed to reconstruct each perturbed fiber specklegram. Finally, the performance of the sensing mechanism is evaluated for different radius of the filtering SSMF and force-gauges, what evidences design criteria for these kinds of measuring systems. Results are in agreement with those theoretical and experimental ones previously reported.

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“…These results are in agreement and are complementary to the experimental ones previously shown in [24,25,36]. From Fig.…”

Section: Fiber Specklegram Analysissupporting

confidence: 93%

“…This procedure evidences clear design criteria for these kinds of measuring systems and, the effects of the force-gauges in their performance. Additionally, results are in agreement with those recently published showing that the sensitivity of the FSS depends on spatial speckle filtering window [36].…”

Section: Introductionsupporting

confidence: 93%

Numerical modeling of fiber specklegram sensors by using finite element method (FEM)

et al. 2016

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“…3(a) as the brown dashed curve, which matches to the above discussions very well. Previously, we used a simplified descriptive model to explain this dependency of the sensitivity 10 . The result presented here, in contrast to previous research 9–12 , provides a modified power-flow model that incorporates the effect of external perturbations, which can be used as a guide for future optical speckle sensor design.…”

Section: Resultsmentioning

confidence: 99%

Power Flow in a Large-Core Multimode Fiber under External Perturbation and its Applications

Qian

Yang

Zhong

et al. 2017

Sci Rep

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Large core optical multimode fiber provides benefits such as a large light-coupling tolerance, easy handling, and delivery of higher light power without undesirable nonlinear effects. In this research, we exploit the effects of external perturbation on the power flow within the large core fiber and present two relevant applications, namely a perturbation sensor and a doughnut beam tuner. Since conventional multimode fiber power flow model does not take into consideration the perturbation effect, we modify the power flow model so that the influence of time varying perturbation can be theoretically analyzed. Based on our theory, we further conduct the numerical simulation and experiments on these two applications. For the fiber vibration sensor, the proposed numerical model shows that the sensor sensitivity depends on the intensity profile of the launched beam and also the higher-order harmonics that were not reported previously can become interferences to affect the signal. For the beam tuner application, we prove both theoretically and experimentally that the doughnut intensity profile at the fiber output can be tuned in real-time by applying external perturbations to the fiber. We expect that the results can be useful to further exploit the external perturbation on large core fiber in various applications.

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“…While the implementation of static multimode fibers can help reduce a source's dynamic speckle [26] by carefully determining suitable fiber lengths, it is more beneficial to utilize dynamic methods. This is primarily due to the speckle's heightened sensitivity to external disruptions within the multimode fiber [27]. Moreover, dynamic strategies can help suppress speckle caused by the multimode fiber itself.…”

Section: Introductionmentioning

confidence: 99%

Record-High Efficiency Speckle Suppression in Multimode Fibers Using Cascaded Cylindrical Piezoelectric Ceramics

Yang,

Li,

et al. 2024

Photonics

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We present a technique that utilizes cascaded resonant cylindrical piezoelectric ceramics and multimode optical fibers wound around them to effectively mitigate laser speckle. By precisely driving the ceramics at their resonant frequencies and inducing comprehensive mode scrambling within the multimode fiber, we achieve a remarkable speckle suppression efficiency of up to 94%. To the best of our knowledge, this sets a new benchmark among various methods aimed at suppressing the speckle of a coherent light. Our study thoroughly explores variables influencing efficiency, including the cascading number of piezoelectric ceramics, driving voltage, fiber core diameter, and more. This method has significant promise for diverse applications that require efficient and fast control of speckle contrast.

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Investigation on sensitivity enhancement for optical fiber speckle sensors

Cited by 9 publications

References 32 publications

Numerical modeling of fiber specklegram sensors by using finite element method (FEM)

Numerical modeling of fiber specklegram sensors by using finite element method (FEM)

Power Flow in a Large-Core Multimode Fiber under External Perturbation and its Applications

Record-High Efficiency Speckle Suppression in Multimode Fibers Using Cascaded Cylindrical Piezoelectric Ceramics

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