fibre optic technology is rapidly evolving, driven mainly by telecommunication and sensing applications. excellent reliability of the manufacturing processes and low cost have drawn ever increasing attention to fibre-based sensors, e.g. for studying mechanical response/limitations of aerospace composite structures. Here, a vector bending and orientation distinguishing curvature sensor, based on asymmetric coupled multi-core fibre, is proposed and experimentally demonstrated. By optimising the mode coupling effect of a seven core multi-core fibre, we have achieved a sensitivity of − 1.4 nm/° as a vector bending sensor and − 17.5 nm/m −1 as a curvature sensor. these are the highest sensitivities reported so far, to the best of our knowledge. In addition, our sensor offers several advantages such as repeatability of fabrication, wide operating range and small size and weight which benefit its sensing applications. Mechanical structures are becoming more and more complex with the introduction of intricate geometries and composite materials 1. Fibre reinforced polymers are composites used in almost every type of advanced engineering structures, with their usage ranging from aircraft, helicopters and spacecraft through to boats, ships and civil infrastructure such as bridges and buildings. They are made with reinforcement fibres among the several types of composites 2,3 that are embedded in a polymer resin (mostly epoxy). Composite materials represent a growing piece of the aerospace material pie. They reduce weight and increase fuel efficiency while being easy to operate, design, shape, and repair. Thus, the study of the mechanical behaviour of these structures has enormous significance. In order to obtain the required level of performance for flight structures, detailed knowledge of material limitations, structural stability and strength aspects is required. Key sources of information on the mechanical performance are sensors based on electronic technology 4-6. Some of the benefits of this type of sensor include accuracy, a wide variety of sizes and shapes, and a simple operating principle. However, they also have several critical shortages. Their performance is affected by humidity, temperature and hysteresis, repeatability and accuracy fall with prolonged use, and also they can be damaged by statics or current overloads. Another constraint is that they cannot work in the presence of electromagnetic fields. Over the last few years, optical fibre sensors (OFSs) have emerged as an alternative to their electronic equivalents in the process of testing material limitations for engineering structures 7,8. Fibre-based sensors can be used to measure strain, temperature, pressure, bending and other quantities 9,10. Such sensors are normally interrogated by coupling the light from a laser (often a single-frequency fibre laser) or from a superluminescent source. The
Random scattering of light in disordered media can be used for highly sensitive speckle-based wavemeters and spectrometers. However, the multiple scattering events that fold long optical paths within a compact space also make such devices exceedingly sensitive to vibrations and small disturbances to the disordered media. Here, we show how scattering can be engineered so that it can be used for a compact computational spectrometer that is largely insensitive to environmental factors. We designed and fabricated a three-dimensional pseudo-random nano-void pattern with 62% scattering efficiency. The controlled amount of multiple scattering ensured a sufficiently long optical path for the target resolution of 100 pm, with optimal long-term stability. The 200-μm-thick scattering silica substrate was integrated in a compact assembly with a low-cost camera sensor. The target resolution was achieved for full spectrum measurements while single wavelengths could be determined with 50 pm resolution. Such tailored scattering systems can improve the trade-off among cost, size, stability, and spectral resolution in computational spectrometers.
We introduce the fabrication and use of microcracks embedded in glass as an optical element for manipulating light propagation, in particular for enhancing waveguide performance in silica integrated optics. By using a femtosecond laser to induce a strong asymmetric stress pattern in silica, uniform cracks with set dimensions can be created within the substrate and propagated along a fixed path. The smoothness of the resulting cleave interface and large index contrast can be exploited to enhance waveguide modal confinement. As a demonstration, we tackle the longstanding high bend-loss issue in femtosecond laser written silica waveguides by using this technique to cleave the outer edge of laser written waveguide bends, to suppress radiative bend loss. The microcrack cross section is estimated to be 15 μm in height and 30 nm in width, for the 10 $$\times$$ × 10 μm waveguides. At 1550 nm wavelength, losses down to 1 dB/cm at 10 mm bend radius were achieved, without introducing additional scattering. Both the cleave stress pattern and waveguide are fabricated with the same multiscan writing procedure, without requiring additional steps, and re-characterisation of the waveguides after 1 year confirm excellent long term performance stability.
This paper puts forward the detecting and fault diagnosis method for GIS. The mentioned method detects and diagnoses faults by detecting abnormal vibration of the GIS. The paper gives out to diagnose the different fault types of the GIS, and make fingerprints for the GIS by monitoring these apparatus. The collected vibration signal was used in the mechanical defect diagnosis, which has proved its effectiveness and precise. This method would be of significance to find out potential faults and fault positioning of GIS in early stage.
The common challenge for reconstructive spectrometers is achieving high spectral resolution without sacrificing device stability, size and costs. Here a fully integrated scattering chip-based spectrometer build on Raspberry Pi platform is designed and implemented. It exhibits no dependence on temperature and humidity (22.7-23.8 o C and 39.5-41 % Rh), is confined in small space (box 50 × 35 × 35 mm) and can reconstruct spectra with resolution up to 0.05 nm (50 pm). The only instability: mechanical micro-movements were compensated by applying pixel binning and device could still reconstruct spectra from binned pictures as small as 32 × 24 pixels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.