Off-axis ultraviolet-written thin-core fiber Bragg grating for directional bending measurements

Zhang, Lisong; Qiao, Xueguang; Liu, Qinpeng; Shao, Min; Jiang, Youhua; Huang, Dong

doi:10.1016/j.optcom.2017.09.061

Cited by 17 publications

(4 citation statements)

References 16 publications

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“…Cladding modes can be produced with an asymmetric FBG, also known as Eccentric FBGs and aforementioned TFBGS. Both grating types can measure bending without PM fibers [95][96][97][98].…”

Section: Configurations and Applicationsmentioning

confidence: 99%

Optical Fiber Sensors by Direct Laser Processing: A Review

Pallarés-Aldeiturriaga

Roldán-Varona

Rodŕıguez-Cobo

et al. 2020

Sensors

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The consolidation of laser micro/nano processing technologies has led to a continuous increase in the complexity of optical fiber sensors. This new avenue offers novel possibilities for advanced sensing in a wide set of application sectors and, especially in the industrial and medical fields. In this review, the most important transducing structures carried out by laser processing in optical fiber are shown. The work covers different types of fiber Bragg gratings with an emphasis in the direct-write technique and their most interesting inscription configurations. Along with gratings, cladding waveguide structures in optical fibers have reached notable importance in the development of new optical fiber transducers. That is why a detailed study is made of the different laser inscription configurations that can be adopted, as well as their current applications. Microcavities manufactured in optical fibers can be used as both optical transducer and hybrid structure to reach advanced soft-matter optical sensing approaches based on optofluidic concepts. These in-fiber cavities manufactured by femtosecond laser irradiation followed by chemical etching are promising tools for biophotonic devices. Finally, the enhanced Rayleigh backscattering fibers by femtosecond laser dots inscription are also discussed, as a consequence of the new sensing possibilities they enable.

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“…Cladding modes can be produced with an asymmetric FBG, also known as Eccentric FBGs and aforementioned TFBGS. Both grating types can measure bending without PM fibers [95][96][97][98].…”

Section: Configurations and Applicationsmentioning

confidence: 99%

Optical Fiber Sensors by Direct Laser Processing: A Review

Pallarés-Aldeiturriaga

Roldán-Varona

Rodŕıguez-Cobo

et al. 2020

Sensors

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“…Recently, a new configuration for fiber shape sensors, based on eccentric FBGs (eFBGs) [26][27][28][29], has been proposed by Waltermann et al [30]. In this configuration, several highly-localized FBGs are inscribed off-axis inside the core of a single-mode fiber at different angular positions.…”

Section: Introductionmentioning

confidence: 99%

“…In this configuration, several highly-localized FBGs are inscribed off-axis inside the core of a single-mode fiber at different angular positions. Unlike standard FBG shape sensors, which rely on changes in the Bragg wavelength, eFBG sensors are based on changes in the spectral intensity at Bragg wavelengths [26,[28][29][30]. Currently, shape deformations in eFBG shape sensors are calculated based on the mode-field displacement method (MFD) [27,30].…”

Section: Introductionmentioning

confidence: 99%

Shape sensing of optical fiber Bragg gratings based on deep learning

Roodsari

Huck-Horvath

Freund

et al. 2023

Mach. Learn.: Sci. Technol.

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Continuum robots in robot-assisted minimally invasive surgeries provide adequate access to target anatomies that are not directly reachable through small incisions. Achieving precise and reliable shape estimation of such snake-like manipulators necessitates an accurate navigation system, that requires no line-of-sight and is immune to electromagnetic noise. Fiber Bragg Grating (FBG) shape sensing, particularly eccentric FBG (eFBG), is a promising and cost-effective solution for this task. However, in eFBG sensors, the spectral intensity of the Bragg wavelengths that carries the strain information can be affected by undesired bending-induced phenomena, making standard characterization techniques less suitable for these sensors. We showed in our previous work that a deep learning model has the potential to extract the strain information from the eFBG sensor's spectrum and accurately predict its shape. In this paper, we conducted a more thorough investigation to find a suitable architectural design of the deep learning model to further increase shape prediction accuracy. We used the Hyperband algorithm to search for optimal hyperparameters in two steps. First, we limited the search space to layer settings of the network, from which, the best-performing configuration was selected. Then, we modified the search space for tuning the training and loss calculation hyperparameters. We also analyzed various data transformations on the network's input and output variables, as data rescaling can directly influence the model's performance. Additionally, we performed discriminative training using the Siamese network architecture that employs two CNNs with identical parameters to learn similarity metrics between the spectra of similar target values. The best-performing network architecture among all evaluated configurations can predict the shape of a 30cm long sensor with a median tip error of 3.11mm in a curvature range of 1.4m−1 to 35.3m−1.

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“…The optical fiber curvature sensors are a good candidaters attributing to their outstanding features, such as small volume, highly responding speed and high sensitivity. To deal with growing demands for accurate measurement curvature, many solutions have been attempted mainly utilizing fiber Bragg gratings (FBGs), [1][2][3] long period fiber grating (LPFGs), 4,5 and photonic crystal fiber. 6,7 In generally, the curvature sensors based on gratings characterize low bending sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Fiber curvature sensor based on concave‐heterotypic cascaded fiber Sagnac interferometer

Ruan

2020

Micro & Optical Tech Letters

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A fiber optical curvature sensor comprising a concave‐heterotypic cascaded fiber structure built into Sagnac loop is demonstrated experimentally. A section of multimode fiber is sandwiched between the single mode fiber and polarization maintaining fiber in order to construct the concave‐heterotypic cascaded fiber structure. The concave structure presented is used to effectively excite guided modes. The spectra of the proposed bending sensor will shift toward long wavelength with curvature. The measured the curvature sensitivity of 11.6 nm/m−1 has been achieved. The proposed curvature sensor characterizes cost‐efficient, simple fabrication process and can be used for health monitoring in civil engineering.

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Off-axis ultraviolet-written thin-core fiber Bragg grating for directional bending measurements

Cited by 17 publications

References 16 publications

Optical Fiber Sensors by Direct Laser Processing: A Review

Optical Fiber Sensors by Direct Laser Processing: A Review

Shape sensing of optical fiber Bragg gratings based on deep learning

Fiber curvature sensor based on concave‐heterotypic cascaded fiber Sagnac interferometer

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