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Lorentzian demodulation algorithm for multimode polymer optical fiber Bragg gratings
摘要： For strain sensing applications, we develop a simple and accurate Lorentzian demodulation algorithm for fiber Bragg gratings (FBGs) inscribed in multimode optical fibers. As multimode FBG spectra generally exhibit multiple peaks, simply tracking some particular spectral peaks (i.e., maximum detection) results in measurement failure when the strain is large. Here, using an FBG inscribed in a perfluorinated graded-index multimode polymer optical fiber, we experimentally evaluate the new method by comparing its performance with those of other demodulation algorithms, such as the maximum and centroid detection methods. Finally, using this method, we demonstrate the accurate measurement of strain of up to 1.0%.
关键词： fiber Bragg gratings,FBG,Lorentzian demodulation algorithm,strain sensing,multimode polymer optical fiber Bragg gratings
更新于2025-11-28 14:24:03
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Fiber laser based on a fiber Bragg grating and its application in high-temperature sensing
摘要： A fiber laser based on an FBG fabricated by femtosecond laser and a Sagnac loop as cavity mirrors is demonstrated. The fiber laser can work stably as a temperature sensor at 1000 ℃ after the FBG was annealed at 1100 ℃. The wavelength of the fiber laser had a quadratic dependence on temperature from room temperature to 1000 ℃. The temperature–wavelength had a good linear relationship from 300 ℃ to 1000 ℃. Its sensing sensitivity was about 15.9 pm/℃.
关键词： Optical fiber lasers,Fiber Bragg gratings,High temperature sensors
更新于2025-11-28 14:23:57
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Long tapered fiber with array of FBG
摘要： A tapered optical fiber with an adiabatic transition from single-mode to a few-mode part has been fabricated with an array of fiber Bragg gratings being inscribed during the drawing process. We demonstrate that the propagating optical signal remains single-mode along the tapered fiber FBG array even in a multimode part of it. The spectral width of the reflected signal from the tapered optical fiber is 4 nm. The level of the reflected signal is up to 5% at some wavelengths.
关键词： Tapered optical fibers,Fiber optics sensors,Fiber Bragg gratings
更新于2025-11-28 14:23:57
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Experimental Analysis of Bragg Reflection Peak Splitting in Gratings Fabricated Using a Multiple Order Phase Mask
摘要： We performed an experimental analysis of the effect of phase mask alignment on the Bragg grating reflection spectra around the wavelength of λB = 1560 nm fabricated in polymer optical fiber by using a multiple order phase mask. We monitored the evolution of the reflection spectra for different values of the angle φ by describing the tilt between the phase mask and the fiber. We observed that the peak at λB is split into five separate peaks for the nonzero tilt and that separation of the peaks increases linearly with φ. Through comparison with theoretical data we were able to identify the five peaks as products of different grating periodicities, which are associated with the interference of different pairs of diffraction orders on the phase mask.
关键词： phase mask,polymer fibers,Fiber Bragg gratings
更新于2025-11-28 14:23:57
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Smart Optical Catheters for Epidurals
摘要： Placing the needle inside the epidural space for locoregional anesthesia is a challenging procedure, which even today is left to the expertise of the operator. Recently, we have demonstrated that the use of optically sensorized needles significantly improves the effectiveness of this procedure. Here, we propose an optimized configuration, where the optical fiber strain sensor is directly integrated inside the epidural catheter. The new design allows the solving of the biocompatibility issues and increases the versatility of the former configuration. Through an in vivo study carried out on a porcine model, we confirm the reliability of our approach, which also opens the way to catheter monitoring during insertion inside biological spaces.
关键词： medical optics instrumentation,fiber optics sensors,clinical applications,fiber Bragg gratings
更新于2025-09-23 15:22:29
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Impact Localization System for Composite Barrel Structure using Fiber Bragg Grating Sensors
摘要： Composite barrel structures are widely used in manufacturing of aircrafts and spacecrafts, the localization of impact on composite barrel structures are essential for structure health monitoring and safety assurance. In this paper, an LVI localization system was established on a composite barrel structure with fiber Bragg grating sensors, by analyzing the relationship between the wavelet packet energy spectrum of LVI response signals monitored by FBG sensors and corresponding impact locations on composite barrel structure, the zeroth node’s energy was found to be sensitive to LVI location, and an impact localization method for composite barrel structure which use the zeroth node’s energies as LVI feature values to predict the LVI locations by means of support vector regression (SVR) was proposed. The performance of the zeroth node’s energy based localization method were compared with localization methods that based on the energy of the fourth node which covers the natural frequency of the composite barrel structure or the total energy of frequency domain. The proposed localization method based on the zeroth node’s energy and SVR demonstrates an effective and practical means for localization of LVI on composite barrel structure with low sampling rate fiber bragg grating sensors and small computation.
关键词： Composite barrel structure,Wavelet analysis,Fiber Bragg gratings.,Impact localization
更新于2025-09-23 15:22:29
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Real-time Surface Shape Sensing for Soft and Flexible Structures using Fiber Bragg Gratings
摘要： In this paper, we present a new soft and flexible sensor which can reconstruct its surface shape in real-time. A single-core optical fiber with fiber Bragg gratings (FBGs) is capable of detecting sparse local strains at high bandwidth using wavelength-division multiplexing (WDM). The fiber was embedded into an elastomeric substrate to reconstruct its global surface morphology. Finite element analysis (FEA) was used to determine the design parameters, and also to validate the unique mapping from sparse strain measurements to the continuum shape of the sensor. To simplify the fabrication and error compensation process without precise/prior knowledge of the FBG locations in the sensor, machine learning-based modelling was applied. This enables real-time, robust and reliable shape reconstruction. It is demonstrated to outperform various applications of electronics-based sensors which require sophisticated electrode wiring and noise reduction. Experiments were performed to evaluate the sensing accuracy and repeatability.
关键词： Soft Sensors and Actuators,Flexible Robots,Surface Shape Sensing,Fiber Bragg Gratings
更新于2025-09-23 15:22:29
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2nd-order random lasing in a multimode diode-pumped graded-index fiber
摘要： Raman lasing in a graded-index fiber (GIF) attracts now great deal of attention due to the opportunity to convert high-power multimode laser diode radiation into the Stokes wave with beam quality improvement based on the Raman clean-up effect. Here we report on the cascaded Raman generation of the 2nd Stokes order in the 1.1-km long GIF with 100-μm core directly pumped by 915-nm diodes. In the studied all-fiber scheme, the 1st Stokes order is generated at 950–954 nm in a linear cavity formed at GIF ends by two fiber Bragg gratings (FBGs) securing beam quality improvement from M2 ≈ 30 to M2 ≈ 2.3 due to special transverse structure of FBGs. The 2nd Stokes wave is generated either in linear (two FBGs) or half-open (one FBG) cavity with random distributed feedback via Rayleigh backscattering. Their comparison shows that the random lasing provides better beam quality and higher slope efficiency. Nearly diffraction limited beam (M2 ≈ 1.6) with power up to 27 W at maximum gain (996 nm), and 17 W at the detuned wavelength of 978 nm has been obtained, thus demonstrating that the 2nd-order random lasing in diode-pumped GIF with FBGs provides high-efficiency high-quality beam generation in a broad wavelength range within the Raman gain spectral profile.
关键词： laser diode,fiber Bragg gratings,beam quality,graded-index fiber,Raman lasing,random distributed feedback
更新于2025-09-23 15:21:21
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Suppression of four-wave mixing in a 22?×?10?Gbps dense wavelength division multiplexed system by linearly chirped fiber Bragg gratings
摘要： A scheme comprising two linearly chirped fiber Bragg gratings (LCFBGs) is proposed to suppress four-wave mixing (FWM) effects in a 22×10? Gbps dense wavelength division multiplexed (DWDM) system employing dispersion shifted fiber with 0.2? nm channel spacing. The FWM reduction in our proposed scheme has been studied by varying the input signal power per channel from ? 2 to + 10? dBm. The parameters of LCFBGs are optimized to obtain a maximum quality factor for all 22 channels. The proposed method is effective even at high input power (10?dBm) and provides a simple, cost effective way to improve the transmission performance in DWDM system.
关键词： Dense wavelength division multiplexing (DWDM),Dispersion,Four wave mixing (FWM),Chirped fiber Bragg gratings,Channel spacing
更新于2025-09-23 15:21:21
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Polymer Fiber Optic Sensors – A Mini Review of their Synthesis and Applications
摘要： Fiber optic sensors (FOSs) are optical fiber based sensing devices that have been widely used to detect physical, chemical and biological parameters. Polymer optical fibers (POFs), an important type of optical fibers, have been stifled their talents in the field of optical sensing due to the overwhelming popularity of glass optical fibers (GOFs). The unique physical and chemical properties of POFs start attracting interests to be utilized in the fabrication of high performance sensors in recent years. This article reviews the recent progress of POFs based FOSs. In particular, the article will focus on novel techniques implemented on the POF sensor fabrication, including monolayer graphene, evanescent wave absorption, localized surface plasmon resonance and fiber Bragg grating.
关键词： Localized surface plasmon resonance,Fiber Bragg gratings,Evanescent wave,Microstructured polymer optical fiber,Polymer fiber optic sensor
更新于2025-09-23 15:21:01