- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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PUSH-PULL PHENOMENON OF A DIELECTRIC PARTICLE IN A RECTANGULAR WAVEGUIDE
摘要： The electromagnetic force acting on a Rayleigh particle placed in a rectangular waveguide is studied. The particle is excited using the lowest order TE 10 mode. It is determined that the particle is laterally trapped at the high intensity region of the electric ?eld and either pushed away from or pulled toward the light source. This push-pull phenomenon depends on whether the frequency of the light wave is above or below the cuto? frequency (i.e., the particle can be pushed or pulled by tuning the frequency). While conventional optical tweezers rely on a balance of scattering and gradient force in the propagation direction, the phenomenon predicted here switches between the two forces near the lowest cuto? in a waveguide.
关键词： TE 10 mode,electromagnetic force,rectangular waveguide,gradient force,optical tweezers,scattering force,Rayleigh particle,push-pull phenomenon
更新于2025-09-16 10:30:52
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Distributed optical fiber sensing: Review and perspective
摘要： Over the past few decades, optical fibers have been widely deployed to implement various applications in high-speed long-distance telecommunication, optical imaging, ultrafast lasers, and optical sensors. Distributed optical fiber sensors characterized by spatially resolved measurements along a single continuous strand of optical fiber have undergone significant improvements in underlying technologies and application scenarios, representing the highest state of the art in optical sensing. This work is focused on a review of three types of distributed optical fiber sensors which are based on Rayleigh, Brillouin, and Raman scattering, and use various demodulation schemes, including optical time-domain reflectometry, optical frequency-domain reflectometry, and related schemes. Recent developments of various distributed optical fiber sensors to provide simultaneous measurements of multiple parameters are analyzed based on their sensing performance, revealing an inherent trade-off between performance parameters such as sensing range, spatial resolution, and sensing resolution. This review highlights the latest progress in distributed optical fiber sensors with an emphasis on energy applications such as energy infrastructure monitoring, power generation system monitoring, oil and gas pipeline monitoring, and geothermal process monitoring. This review aims to clarify challenges and limitations of distributed optical fiber sensors with the goal of providing a pathway to push the limits in distributed optical fiber sensing for practical applications.
关键词： energy applications,Brillouin scattering,Rayleigh scattering,Raman scattering,optical time-domain reflectometry,distributed optical fiber sensing,optical frequency-domain reflectometry
更新于2025-09-16 10:30:52
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Mass Producible Low-Loss Broadband Optical Waveguides in Eagle2000 by Femtosecond Laser Writing
摘要： Optical waveguides were fabricated in alkaline earth boro-aluminosilicate glass, by femtosecond laser direct writing, with varying pulse energy and scan velocity. A spectral characterization, from 500 nm to 1700 nm, was made in order to determine their losses and understand its dependence on the processing parameters. Three major loss mechanisms were identified. At longer wavelengths, loss is mainly due to weak coupling. On the other hand, the behavior at shorter wavelengths is governed by propagation loss due to Rayleigh scattering, which was shown to be practically eliminated (<0.05 dB· cm?1· μm4) at higher scan velocities. Bulk absorption was also found to have an influence in the propagation losses at higher wavelengths. The combination of intermediate pulse energies (between 125-250 nJ) and high scan velocities (above 6 cm/s) allowed the fabrication of optical waveguides offering low losses across the entire range of wavelengths tested, facilitating applications that require larger wavelength working bands. Furthermore, since optimal fabrication conditions are achieved at higher scanning velocities, mass production with reduced fabrication times can be achieved.
关键词： femtosecond laser direct writing,Rayleigh scattering,propagation loss,Coupling loss,Mie scattering,integrated optics,low-loss broadband optical waveguides,mass production
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Achievement of Very Smooth Cavity Sidewalls by UV Picosecond Laser Micromachining
摘要： Achievement of very smooth cavity sidewalls by UV picosecond laser micromachining. As a contactless and maskless method generating a reduced heat affected zone compared to nanosecond laser, ultrafast laser micromachining is widely used for rapid prototyping and materials processing. Today, most research and development works is devoted to study and control LIPPS occurring at the surface of the cavity bottom. But for many applications, there is a strong need to produce highly smooth sidewalls like for microelectronic sample preparation, microfluidics, waveguides, etc.. A laser based technology allowing to obtain very smooth surfaces (Ra of ~3 nm) already exists but it involves melting of a significant volume of material. So far, to the best of our knowledge, no parametric study aiming at minimizing the roughness of picosecond laser micromachined sidewalls in silicon has been performed. In the present work, picosecond laser micromachining (532 nm and 343 nm) of cavity sidewalls in silicon is studied. The evolution of the surface roughness is deeply investigated experimentally and theoretically as a function of laser and scanning parameters. We demonstrate that RaX, which is measured along the scanning laser beam direction, can be minimized by increasing laser beam overlap and the crater size, in accordance with a simple geometrical model. Experimentally, the minimum RaX is obtained for a beam overlap of ~80% and the largest crater sizes. Beyond 80%, we observed a roughness degradation which is probably due to two main phenomena. The first involves the interaction between the laser beam and the debris, which deteriorates the beam quality. The second is related to the highly heterogeneous ablation occurring for large overlaps, which induces a rough surface. Along the beam propagation direction, the sidewall is characterized by a relatively high waviness which induces a more important height variation than the roughness. The waviness depends mainly on the Rayleigh length. Thus, it can be reduced by using a large focal spot radius and a short wavelength. Once the sidewall is finished, the surface topology does not vary much with the laser micromachining time. Overall, smooth and homogeneous surfaces can be produced by choosing a beam overlap close to 80%. The best results were obtained at 343 nm, which allows to extend the Rayleigh zone, to increase the laser absorption on the sidewall asperities and to improve the induced cleaning thanks to a more confined interaction. The present work demonstrates that very low roughness (< 40 nm) can be achieved on sidewalls of cavities by picosecond laser micromachining. In addition this approach allows the roughness tuning. As it is based on a geometrical model, it is extendable to other materials as long as the surface melting, which may erase the induced periodic structuring, is not significant. This tuning possibility can be useful to modify the surface properties, such as reflectivity, friction and wettability, and therefore adapt the sidewall to different applications.
关键词： smooth cavity sidewalls,waviness,silicon,UV picosecond laser,roughness,micromachining,Rayleigh length
更新于2025-09-12 10:27:22
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Analysis of Tyndall effect on output performance of P.macrophylla Benth. dye-sensitized solar cells
摘要： The study demonstrates the impact that maximum light-scattering effect has on negligible amount of P.macrophylla B. dye. It investigated the influence of particle size on intensity via the exponential factor of the intensity of Rayleigh scattering. The study adopted two approaches of experimental and theoretical investigations, while two sets of dye sensitive solar cells (DSCs) were employed. One set of DSCs (crude) had an organic light scattering layer attached while the second (hexane) set was without the light scattering layer. The outcome of the experiment revealed a significant increase in photovoltaic performance of DSCs which had an improvised scattering layer. The short circuit current (Isc) of P.macrophylla B. crude was 64.7% higher than that of the hexane DSCs, the open circuit voltage (Voc) of the crude DSC was more than 50% greater than the hexane DSCs. Although, hexane DSCs had a better fill factor (ff), the output performance of the crude DSCs was thrice that recorded by hexane DSCs. The implication of this study is that, theoretical models can be used for simulating optimal angles of incident in DSCs which can be maximized for higher output in further studies.
关键词： Efficiency,Energy harvesting,Rayleigh Scattering,Tyndall Effect Photovoltaics
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Light Scattering Materials as Photoanodes
摘要： Dye-sensitized solar cells (DSSCs) are existing to be a promising alternative to conventional silicon solar cells owing to its ease of fabrication, low cost, along with the additional features like flexible devices and building integrated photovoltaic system [1]. In general, DSSC architecture comprised of semiconducting photoanode, counter electrode (catalyst), and an electrolyte [2, 3]. In DSSC, the quantity of light caught by the dye-sensitized photoanode has a strong influence on the overall performance because the electrons are generated directly from the excited dye molecules by the irradiated sunlight. One of the primary key tasks is to boost the performance of the device by enriching the photon absorption in DSSCs such as the introduction of a tandem structure and the introduction of a light-scattering effect. Among these developments, the light-scattering effect had more attention than others because of an easy method for enhancing light absorption [4–7]. The simple theory of light scattering effect was introduced by Usami [8] in 1997, stating that a new photoelectrode structure consisting of top layer made up of a large sized particle film on the below layer made up of a small sized particle film; the light scattered by the top layer triggered an increase in the light absorption. In initial days, several studies had been focused on the analysis of the light-scattering effect in the DSSCs by using various simulation methods based on the Monte Carlo model, Mie theory, and the many-flux model. Subsequently, the light-scattering effect had been widely used as an important technique to develop the performance of DSSCs [9]. So, the introduction of light scattering and light scattering materials are explained in the following sections.
关键词： Dye-sensitized solar cells,Rayleigh scattering,TiO2,Mie theory,nanoparticles,light scattering,DSSCs,photoanodes
更新于2025-09-12 10:27:22
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Coarse Grained Simulation and Turbulent Mixing || Laser Driven Turbulence in High Energy Density Physics and Inertial Confinement Fusion Experiments
摘要： The mixing of initially separate materials in a turbulent ?ow by the small scales of turbulent motion is a critical and often poorly understood element of many research programs, such as inertial con?nement fusion (ICF), supernova implosions and explosions, and combustion, as well as many other applications in engineering, geophysics, and astrophysics. In typical contexts of interest, we are interested in achieving detailed understanding of interpenetration, hydrodynamical instabilities, and mixing arising from perturbations at the material interfaces, that is, driven by Rayleigh–Taylor (RT), Richtmyer–Meshkov (RM), and Kelvin–Helmholtz (KH) instabilities (buoyancy, shock, and shear induced instabilities, respectively). Laboratory observations typically provide only limited integrated measures of complex nonlinear three-dimensional physical processes, leaving many details and mechanisms unresolved. Carefully controlled computational experiments based on the numerical simulations play a crucial complementary role, providing insight into the underlying dynamics. Collaborative laboratory/computational studies are used to establish predictability of the models in conjunction with the development of frameworks for analysis, metrics for veri?cation and validation, and uncertainty quanti?cation.
关键词： Richtmyer–Meshkov instability,Rayleigh–Taylor instability,inertial con?nement fusion,turbulent mixing,high energy density physics,Kelvin–Helmholtz instability
更新于2025-09-12 10:27:22
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[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Monitoring of the Drilling-Induced Temperature Profile in CFRP Plates Using Distributed Optical Fiber Sensing
摘要： Distributed fiber sensing based on optical frequency-domain reflectometry is proposed for monitoring the two-dimensional temperature profile resulting during drilling carbon reinforced fiber polymers. Experimental results demonstrate the unique features and advantages provided by this technology.
关键词： Scattering,Rayleigh,Temperature,Fiber optics sensors
更新于2025-09-12 10:27:22
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The Influence of Solar Illumination on the Sensitivity of Passive Lidar for Reception of The Scattered Laser Radiation
摘要： We solve the problem of determining the power of the received scattered optical radiation from external laser beams, which propagate in the Earth’s atmosphere, by passive lidar in a weakly turbid transparent atmosphere and also determine the lidar operation radius. Under the night conditions without solar illumination, the lidar operation radius can exceed 2300 km when detecting the beams with powers is about 100 kW. In the presence of solar illumination, the operation radius decreases by an order of magnitude. For a small power of the external beam, the experimental and theoretical data are in good agreement, which makes it possible to extrapolate the obtained theoretical results to larger powers of the external beams with allowance for the radiation loss because of the secondary Rayleigh scattering.
关键词： Rayleigh scattering,scattered laser radiation,detection radius,passive lidar,solar illumination
更新于2025-09-11 14:15:04
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Dynamically Tunable Plasmon-Induced Transparency Based on Radiative–Radiative-Coupling in a Terahertz Metal–Graphene Metamaterial
摘要： The thin aluminum liners with an aspect ratio R/?r (cid:28) 1 have been imploded on the primary test stand (PTS) facility, where R is the outer radius of the liner and ?r is the thickness. The x-ray self-emission images present azimuthally correlated perturbations in the liner implosions. The experiments show that at ?10 ns before the stagnation, the wavelengths of perturbation are about 0.93 mm and 1.67 mm for the small-radius and large-radius liners, respectively. We have utilized the resistive magnetohydrodynamic code PLUTO to study the development of magneto-Rayleigh–Taylor (MRT) instabilities under experimental conditions. The calculated perturbation amplitudes are consistent with the experimental observations very well. We have found that both mode coupling and long implosion distance are responsible for the more developed instabilities in the large-radius liner implosions.
关键词： Z-pinches,thin liner implosion,primary test stand (PTS),magneto-Rayleigh–Taylor instability,magnetohydrodynamic (MHD)
更新于2025-09-11 14:15:04