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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Development of a Highly Stretchable Strain Sensor Based on Patterned and Rolled Carbon Nanotubes
摘要： This paper reports a highly stretchable strain sensor consisting of patterned and rolled carbon nanotubes (CNTs) embedded in an elastomer. To form overlapped lines of CNTs on the elastomer, vertically aligned CNTs (VACNTs) are grown on the patterned catalytic sites and rolled out by a roller. In the initial unloaded state, these lines of CNTs are overlapped with each other. Under loading, the flexible substrate is extended, and the overlapped CNT lines are slid and separated, increasing the electrical resistance. The fabricated sensor showed excellent sensing performances including broad sensing range (>500% strain), high sensitivity (gauge factor >28), high repeatability, and durability. In addition, since the shape of the CNT lines determines the resistance through the deformed lines of CNTs under applied strain, the performance of the sensor can be further improved by optimizing the pattern design. Therefore, the sensor would be an attractive candidate for diverse applications of strain sensors.
关键词： high sensitivity,elastomer,stretchable strain sensor,carbon nanotubes,broad sensing range
更新于2025-09-12 10:27:22
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A Multirange Photodetector Based on the Effect of Photon Dragging Current Carriers in Germanium for High-Power Lasers in the Infrared Range
摘要： A highly efficient model of a photodetector based on the effect of dragging free current carriers by photons in semiconductors is proposed, which makes it possible to quickly change the working length of a crystal element. In this case, it is possible to expand the range of measured pulse durations by reducing or increasing the photodetector sensitivity.
关键词： high-power lasers,photodetector,photon dragging,infrared range,germanium
更新于2025-09-12 10:27:22
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Theoretical and experimental studies of highly selective planar two-dimensional Bragg structures based on dielectric waveguides in the terahertz frequency range
摘要： Based on theoretical approach and three-dimensional modeling using the CST Microwave Studio code, planar dielectric two-dimensional Bragg structures in terahertz frequency range were developed and manufactured. Proof-of-principle electrodynamic experiments on the “cold” testing of these structures were carried out. It is shown that the experimental results are in good agreement with the theoretical predicts, including the existence of the highest Q mode inside the Bragg reflection band in the absence of periodicity defects.
关键词： CST Microwave Studio,Bragg reflection band,planar dielectric two-dimensional Bragg structures,terahertz frequency range,electrodynamic experiments
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Multilayer optical routing by means of vertical directional coupler with long range surface plasmons
摘要： We show that e?cient multilayer optical routing is achievable with long range surface plasmon polaritons (LR-SPP) through an accurate design of vertical directional couplers (VDC). Our theoretical results suggest that by suitably tuning some geometrical parameters, in particular the path length and bend radius, it is possible to obtain a good control on the overall interaction, even in presence of fabrication non-idealities. We present a top-down fabrication process ?ow for LR-SPP multilayer optical circuits, obtained by stacking multiple ultrathin nanometric metal ?lms within a polymeric dielectric background; the overall structure has a good degree of mechanical stability. By pro?ting from the topological advantage given by VDCs, as one of the useful applications of our work, we propose a new optical integrated circuit architecture scheme, capable of connecting two separate circuit paths without in?uencing the geometry or signi?cantly promoting crosstalk with any other path in the middle. The possibility to develop vertically stacked optical integrated circuits upon electronic integrated circuits makes LR-SPPs a good technology for the production of inexpensive and high-density network systems.
关键词： optical integrated circuits,long range surface plasmons,multilayer optical routing,vertical directional coupler
更新于2025-09-12 10:27:22
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Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers
摘要： Organic single crystals with long-range molecular order ensure enhanced carrier mobility and stability as well as emission outcoupling, which makes them attractive as gain medium for electrically pumped organic lasers. Unfortunately, effects of excitonic coupling introduce losses degrading optical performance in crystals, hence higher lasing thresholds are observed compared to amorphous films. Here, crystal doping strategy is investigated as a method to avoid pronounced reabsorption and annihilation losses associated with J-type excitonic coupling, while taking advantage of enhanced exciton transport for efficient energy transfer. Bifluorene-based derivatives linked with acetylene and ethylene rigid bridges are suitable as host and dopant system forming high-quality crystals doped at various concentrations (0.5–11.0%). Enhanced exciton transport in host crystal mediates picosecond host–dopant energy transfer enabling 100% transfer efficiency at lower doping concentrations compared to amorphous films. Amplified spontaneous emission threshold of 1.9 μJ cm?2 in 3.5% doped crystal is enabled by minimized exciton annihilation and emission reabsorption losses at optimal doping concentration.
关键词： long-range energy transport,organic single crystals,organic laser gain materials,amplified spontaneous emission,F?rster resonant energy transfer
更新于2025-09-12 10:27:22
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[IEEE OCEANS 2019 - Marseille - Marseille, France (2019.6.17-2019.6.20)] OCEANS 2019 - Marseille - Extracting the interference components of normal modes in a shallow water waveguide using modified autocorrelation warping transform <sup>*</sup>
摘要： In underwater acoustic signal processing, current attention is on interference components of normal modes which can provide a means to estimate source range or depth. In this paper, we propose a modi?ed warping transform for the autocorrelation function of received signal. Through deducing the expression of the horizontal wavenumber in shallow water waveguide, the proposed warping transform is valid in most shallow water waveguide, not only in an ideal waveguide. Since we warped the autocorrelation function of received signal, we have no need to estimate the arrival time of signal. Note that the phase of the warped function is related to source range. We propose a method based on the proposed warping transform to estimate source range. Simulation results present the effectiveness of the warping transform and the passive source range estimation method.
关键词： autocorrelation function,warping transform,range estimation,interference components of normal modes
更新于2025-09-12 10:27:22
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Quartz Optical Fibers with Increased Content of Fluorine for Fluorimeter Probes
摘要： A method to fabricate quartz optical fibers for probes employed in fluorescence diagnostics of tumors is proposed. It is shown that the sensitivity of fluorimeters in the near-IR spectral range can be increased using quartz–quartz optical fiber probes with the core made of the Heraeus glass and the SiO2–F cladding with an increased content of fluorine in the glass of up 7 wt %. The numerical aperture of such optical fibers amounts to 0.32. The optical fibers are used to develop a prototype of a multifiber high-aperture probe for a laser oncofluorimeter with a relatively high sensitivity in a spectral interval of 900–1100 nm.
关键词： fluorimeter probes,fluorescence diagnostics,quartz optical fibers,fluorine,near-IR spectral range
更新于2025-09-12 10:27:22
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Formation of optical supramolecular structures in a fibre laser by tailoring long-range soliton interactions
摘要： Self-assembly of fundamental elements through weak, long-range interactions plays a central role in both supramolecular DNA assembly and bottom-up synthesis of nanostructures. Optical solitons, analogous in many ways to particles, arise from the balance between nonlinearity and dispersion and have been studied in numerous optical systems. Although both short- and long-range interactions between optical solitons have attracted extensive interest for decades, stable soliton supramolecules, with multiple aspects of complexity and flexibility, have thus far escaped experimental observation due to the absence of techniques for enhancing and controlling the long-range inter-soliton forces. Here we report that long-range soliton interactions originating from optoacoustic effects and dispersive-wave radiations can be precisely tailored in a fibre laser cavity, enabling self-assembly of large numbers of optical solitons into highly-ordered supramolecular structures. We demonstrate several features of such optical structures, highlighting their potential applications in optical information storage and ultrafast laser-field manipulation.
关键词： supramolecular structures,fibre laser,optoacoustic effects,optical solitons,long-range interactions
更新于2025-09-12 10:27:22
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Silicon photodetector for integrated lithium niobate photonics
摘要： We demonstrate the integration of an amorphous silicon photodetector with a thin film lithium niobate photonic platform operating in the visible wavelength range. We present the details of the design, fabrication, integration, and experimental characterization of this metal-semiconductor-metal photodetector that features a responsivity of 22 mA/W to 37 mA/W over the wide optical bandwidth spanning in the 635 nm–850 nm wavelength range.
关键词： lithium niobate,visible wavelength range,integration,photonics,silicon photodetector
更新于2025-09-12 10:27:22
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Structural evolution of fused silica below the glass-transition temperature revealed by in-situ neutron total scattering
摘要： The common belief that glass structure is completely frozen-in at room temperature is challenged at both macroscopic and atomic scales. Here, we demonstrate an analytical method to elucidate the fine details of a continuous structural change of fused silica (FS) at temperatures below the glass-transition temperature using in-situ neutron total scattering. We find that the SiO4 tetrahedron expands through the entire temperature range with a local coefficient of thermal expansion of 9.1 × 10?6 K?1, while the average medium-range distance, derived from the first sharp diffraction peak of the structure factor, expands at a rate of 21 × 10?6 K?1. Such an expansion difference reflects glass-structure changes within the "rigid-unit mode" model, where each tetrahedron behaves as a rigid unit and the flexible rotations between rigid units lead to more than two times higher medium-range thermal expansion. We further demonstrate that such rotations change the shape of individual rings, leading to a measurable change in the first sharp diffraction peak (FSDP). This study paves the way to measure the structural changes of other silicate glasses, especially through the glass transition.
关键词： Structural change of fused silica,Short- and medium-range structure,In-situ neutron total scattering,First sharp diffraction peak,Rigid-unit mode
更新于2025-09-12 10:27:22