Session Index

Fibre Bragg gratings (FBGs) are well-established all-fibre devices capable of monitoring a range of parameters in various configurations with high precision incl., strain, temperature, and pressure. Due to the ability to accurately design the phase and amplitude response from FBGs into their spatial refractive index profile, and because of the flexibility to precisely control their length, they can also be used as devices to help correct signal distortion encountered in optical transmission systems resulting from, for example, timing- jitter and chromatic dispersion. The precise control of length can also be utilised to monitor and determine perturbations continuously along their length, in real-time. One such application, demonstrated and researched more extensively in recent years, is the ability to monitor and determine the velocity of rapid chemical reactions and detonation events with a very high degree of spatial precision.

The speed at which shock-fronts advance through a material – the velocity of reaction/detonation – is an important measure for assessing the performance and characteristic behaviour of the material. Optical fibre sensors, incl., FBGs, are proving an excellent diagnostic tool for this purpose too, and because of their small size, they can be used as embedded probes offering minimal physical invasiveness into the compounds and materials being tested. In this talk we will review and discuss our research in this area and discuss probes based on both uniform and chirped FBGs, bare fibres, and rare-earth doped fibres. We will discuss how these probes are designed and discuss the advantages and limitations of each of them depending on the exact application and system they are designed for. We will show that using a new approach we developed based on uniform FBGs it is possible to achieve spatial uncertainties below ±10m when determining the position of the perturbation on the FBGs during high-speed events with velocities in excess of ~6mm/s (6km/s).

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Scattering is the most common phenomenon in optics, but it has not been widely adopted in online real-time scenarios. In view of the potential for real-time intelligent scattering detection, this paper proposes a conceptual structured light scattering detection device.

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An epilayer of Zinc Gallium oxide with a thickness of 100 nm was successfully grown on a c-plane sapphire substrate using the metalorganic chemical vapor deposition technique. The performance of the designed photodetectors was evaluated by measuring the photocurrent under various bias voltages and distinct x ray flux intensities: ranging from 107 to 1011 counts per sec. Additionally, the transient response of the photodetector was examined. The findings revealed that these designed photodetectors exhibited higher sensitivity compared to detectors based on gallium oxide.

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We demonstrated neoteric point of care fulfilling waveguide nanogold linked immunosorbent assay optical biosensor to endow ultra-sensitive and prompt detection of crucial biomarkers such as Procalcitonin. The proposed sensor reveals excellent biosensing performance with a negligible low non-specific adsorption, low record LOD of value 48.7 fg/mL and short detection time of nearly 9 minutes.

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This study focuses on generating random modulated pulses using a gain-switched semiconductor laser with a recirculating delay lines (RDL) interferometer designed for pulsed lidar application. The RDL structure's multi-interference bestows the random modulate pulse with high modulation and low-correlation characteristics, well-suitable for pulsed lidar unambiguity ranging and jamming resistance. By adjusting laser bias currents and RDL delay lengths, we assess two distinct scenarios: one optimizing precision for 3D reconstruction, and another emphasizing low correlation for anti-jamming. Finally, we successfully demonstrate 3D imaging, showcasing exceptional precision in capturing intricate detail, such as the Marseille statue.

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Photomultiple narrowband organic photodiodes (PM-NOPDs) are fabricated using a
planar heterojunction structure. The bottom PM6 layer selects excitons, while the top P3HT: PC70BM layer acts as a photomultiplication layer. The device functions with electron tunneling injection caused by hole accumulation near the Ag electrode. Because only selected exciton undergoes photomultiplication, the detector exhibits a high external quantum efficiency of 5840%, a narrowband peak at 680 nm, and a spectral response of over 30 A/W at -5 V. This approach allows for the fabrication of high-performance PM-NOPDs with low bias, low noise, and high speed.

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Guided mode resonance (GMR) gratings are gaining traction in sensing applications. This study outlines an optimal, easy-to-fabricate one-dimensional GMR grating with enhanced performance using thin films. Its design boosts the sensing performance with figure of merit values reaching hundreds of thousands. Simulations show an optimized grating with a sensitivity of 252 and a narrow bandwidth of 0.0002 nm. Remarkably, at a 50° incident angle, its figure of merit reaches 839,666, outperforming traditional GMR sensors significantly. Simulations at 60° and 70° incident angles expand its applicability, offering insights into the sensor's varied performance scenarios.

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In this article, the integration of the brillouin optical time-domain analysis (BOTDA) and the phase-sensitive optical time domain reflectometry (Ф-OTDR) distributed fiber sensing systems is discussed. By combining the two systems and sharing common instruments, the cost of the experiments is minimized, enabling the sensing of three parameters: temperature, strain, and vibration on the same 18.7 km fiber.

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