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[IEEE 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Saint Petersburg, Russia (2018.10.22-2018.10.23)] 2018 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Monitoring of Flowing Media State by Refraction Phenomenon
摘要： A paper the refraction phenomenon for condition control of flowing media is considered. The peculiarity of flowing liquid condition control by displacement of the light-shadow boundary are determined. The results of experimental investigations are presented.
关键词： refraction,refractive index,full internal reflection,stream of fluid flow
更新于2025-09-23 15:23:52
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Dual functional optofluidic platform based on light-actuated air plug
摘要： Optical systems based on fluid-fluid interface are gaining great attention because they offer added advantages such as dynamic, reconfigurable, and self-healing capabilities with less complex fabrication steps compared to the solid based optical elements. Moreover, cost-effectiveness and ease of miniaturization pave a potential route towards the realization of portable optical and optofluidic devices. However, a single optofluidic device having remotely controlled multifunctional capabilities remains a challenge. We demonstrate an optofluidic multifunctional strategy, which could operate either as an optical switch or a tunable liquid lens. The principle relies on light-controlled volumetric change of an air plug confined in a minichannel filled with water. For the optical switch, volumetric change of the air plug modulates total internal reflection. A temperature difference of only 0.2 °C is sufficient for a subsecond switching time (0.6 ± 0.1 s). For the liquid lens, the change of plug size acts as an actuator to control the meniscus shape of the liquid. Upon heating or cooling, the meniscus develops a convex or a concave lens respectively. A temperature difference of 0.1–0.7 °C is sufficient for realizing tunability in the focal length. The demonstrated strategy is simple, cost-effective, non-contact and the device could be operated at room temperature.
关键词： Optical switch,Total internal reflection,Liquid lens
更新于2025-09-23 15:23:52
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[IEEE NAECON 2018 - IEEE National Aerospace and Electronics Conference - Dayton, OH, USA (2018.7.23-2018.7.26)] NAECON 2018 - IEEE National Aerospace and Electronics Conference - Electromagnetic Propagation across an Achiral/Chiral (Dispersive) Boundary Using Phasor Approach to Fresnel Coefficients
摘要： Electromagnetic propagation across an achiral/chiral interface has been studied to evaluate Fresnel coefficients and examine the propagation characteristics. Extending the problem to include dispersive chiral dielectrics and discrete components may lead to potential applications such as tunable superlenses (with imaging and vision implications) and also devices including chiral Fabry-Perot etalons.
关键词： Fresnel coefficients,chiral Fabry-Perot resonator,metamaterials,chiral media,internal reflection,anomalous Brewster phenomenon
更新于2025-09-23 15:22:29
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Dual-prism based terahertz time-domain attenuated total reflection spectroscopy and its application to characterise the hydration state of L-threonine in solution
摘要： To investigate the hydration state of amino acids, terahertz time-domain attenuated total internal reflection (THz TD-ATR) spectroscopy is often adopted to measure the complex permittivity. However, the classical THz TD-ATR spectroscopy system has only a single ATR prism and requires prism cleaning for different measuring modes, increasing the time consumed and easily introducing errors due to the changing environment. To accelerate the measurements and avoid the influence of environmental fluctuations, in this paper, we designed and built a dual-prism based THz TD-ATR spectroscopy: two ATR prisms with and without samples setting on the optical rail can be sequentially switched to optical systems for easily and rapidly collecting both sample and reference ATR spectra. According to the measurements of deionised water, the dual-prism based THz TD-ATR spectroscopy system can measure the sample complex permittivity rapidly and with high accuracy. The complex permittivity of L-threonine in aqueous solution is measured and analysed via the proposed system, and the hydration numbers of L-threonine solutions in different concentrations are quantitatively characterised. It is believed that the dual-prism based THz TD-ATR technique is a powerful tool for quickly and accurately investigating the hydration of amino acids.
关键词： Terahertz spectroscopy,Complex permittivity,Time-domain attenuated total internal reflection,Amino acid hydration
更新于2025-09-23 15:22:29
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Total Internal Reflection-based Extinction Spectroscopy of Single Nanoparticles
摘要： Here we report a reflection-mode total internal reflection microscopy (TIRM) to measure the extinction spectrum of individual dielectric, plasmonic or light-absorbing nanoparticle, and to differentiate absorption and scattering components from the total optical output. These capabilities were enabled via illuminating the sample with evanescent wave of which the lightpath length was comparable with the size of single nanoparticles, leading to a dramatically improved reflectance change (ΔI/I0) up to tens of percent. It was further found that scattering and absorption of light contributed to bright and dark centroids, respectively, in the optical patterns of single nanoparticles, allowing for distinguishing scattering and absorption components from the extinction spectrum by the use of an appropriate image processing method. In addition, wide-field feature of TIRM enabled the studies on tens of nanoparticles simultaneously with gentle illumination. The present work not only provides a promising and complementary tool for understanding the light-matter interactions at single nanoparticle level, but also expands the applicable scope of total internal reflection-based spectroscopy and microscopy.
关键词： total internal reflection,single nanoparticle spectroscopy,extinction spectroscopy
更新于2025-09-23 15:21:21
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An Ellipsometric Technique with an ATR Module and a Monochromatic Source of Radiation for Measurement of Optical Constants of Liquids in the Terahertz Range
摘要： Measuring the optical constants of liquids, especially water-containing solutions, is very difficult in the terahertz range. The well-known methods of measurement of the refractive index and absorption coefficient in this range include time-domain spectroscopy and Fourier-transform spectrometry. We have developed a highly sensitive ellipsometry method for measuring the optical constants of liquids using the tunable monochromatic radiation from the Novosibirsk free-electron laser. The ellipsometer is supplemented with an internal reflection module for the measurement of highly absorbing samples. The angle of incidence on the sample in the silicon prism of the module has been optimized for maximum sensitivity to parameters to measure. Measurements of the optical constants of various liquids have been performed, and a sensitivity of 0.01 has been demonstrated.
关键词： Internal reflection ellipsometry,Free electron laser,Aqueous solution,Terahertz range
更新于2025-09-23 15:21:21
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Total Internal Reflection-based Extinction Spectroscopy of Single Nanoparticles
摘要： Here we report a reflection-mode total internal reflection microscopy (TIRM) to measure the extinction spectrum of individual dielectric, plasmonic or light-absorbing nanoparticle, and to differentiate absorption and scattering components from the total optical output. These capabilities were enabled via illuminating the sample with evanescent wave of which the lightpath length was comparable with the size of single nanoparticles, leading to a dramatically improved reflectance change (ΔI/I0) up to tens of percent. It was further found that scattering and absorption of light contributed to bright and dark centroids, respectively, in the optical patterns of single nanoparticles, allowing for distinguishing scattering and absorption components from the extinction spectrum by the use of an appropriate image processing method. In addition, wide-field feature of TIRM enabled the studies on tens of nanoparticles simultaneously with gentle illumination. The present work not only provides a promising and complementary tool for understanding the light-matter interactions at single nanoparticle level, but also expands the applicable scope of total internal reflection-based spectroscopy and microscopy.
关键词： total internal reflection,single nanoparticle spectroscopy,extinction spectroscopy
更新于2025-09-23 15:21:01
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Femtosecond Laser-inscribed Non-volatile Integrated Optical Switch in Fused Silica based on Microfluidics-controlled Total Internal Reflection
摘要： We demonstrate a non-volatile optical power switch, fabricated by femtosecond laser inscription in a fused silica substrate, with switching operation based on microfluidics-controlled total internal reflection. The switch consists of crossed waveguides and a rectangular, high aspect ratio microfluidic channel, located at the waveguide crossing. The switching between total internal reflection and transmission at the channel wall is determined by the refractive index of the medium inside the channel. Femtosecond laser inscription allows for co-integration of low-loss optical waveguides and channels with smooth sidewalls and thus the fabrication of low insertion loss switches that are broadband and show low polarization dependent losses. The measured total internal reflection loss of the fabricated switch is about 1.5 dB at the wavelength 1550 nm. The loss due to transmission through the channel filled with refractive index matching liquid is about 0.5 dB. Detailed finite time domain and beam propagation method difference simulations of the switch’s performance indicate that the losses can be further reduced by optimizing its geometry, together with further adjusting the inscription parameters.
关键词： Fused silica,Non-volatile,Single mode waveguides,Total internal reflection,Microfluidics,Femtosecond laser inscription,integrated optical switch
更新于2025-09-19 17:13:59
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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) - Silicon Photonics at the Interface with a Phase Change Material
摘要： Phase change materials (PCMs) have the ability to control the phase [1], polarization [2], amplitude and coloration [3] of light. Examples of such materials are vanadium dioxide (VO2), GeSbTe and AgInSbTe, which can, owing to changes in their refractive indices, alter the properties of light. Although PCMs have been studied in situations where light propagates from a low-index medium (e.g. air) into the material, there are more possibilities when total internal reflection is involved. In this paper, we investigate the interaction between light travelling in a dense medium with a phase change layer, with particular attention paid to interfaces involving silicon. The possibility of tuning and controlling light at the interface with silicon would be of interest for silicon photonics applications.
关键词： silicon photonics,total internal reflection,vanadium dioxide,Phase change materials,polarization
更新于2025-09-16 10:30:52
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Surgical Lamp Design Based on LED Diffuse Transmission Illumination System
摘要： In this article, we have designed a surgical light lens especially for oral surgical illumination. It provides a uniform and wide field of view for illumination during oral surgery. The support system, a set of LEDs and a double free-form surface constituted the lighting system. The double free-form surface is composed of traditional free-form surface, designed total internal reflection lens and diffuse transmission plate, which improves the optical performance of the LED. When the light keeps dispersing the pupil constriction, it eventually causes our eyes to fatigue. The purpose of increasing diffuse transmission is to make the emitted light softer, thus making peoples’ eyes feel more comfortable. Based on the problems mentioned above, a numerical method is proposed as the basis for designing the double free-form surface. First, establishing a mathematical model based on the characteristics of the transmissive surface and the property of the LED. Henceforth, the nonlinear equations for the illumination distribution of the outside surface can be deduced. By solving the equation, the contour of the free-form surface is obtained. Later, we imported the contour into the 3D modeling software Solidworks to rotate so as to get the corresponding model. Finally, the simulation results suggest that the optical uniformity of the double free-form surface is able to reach as much as 86.18%.
关键词： free-form surface,uniform illumination,the total internal reflection (TIR),optical design,Diffuse transmission
更新于2025-09-12 10:27:22