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Stimuli‐responsive structural‐color materials have received widespread attention in information encryption due to the significant color changes under different stimuli. However, the trade‐off between the capacity of information input, security level, cost, and large‐area manufacturing greatly limits the application of structural colors in encryption. Herein, dynamic high‐capacity and high‐resolution encryption are achieved by implementing printed total internal reflection (TIR) structural color and computer‐aided image recognition. The printed TIR microstructures are prepared with relative humidity (RH) responsive polymer, which form a heterogeneous wettability system, and can exhibit vibrant color variation with humidity. As the implemented RH is changed, the printed microstructures will expand or shrink precisely, enabling a full‐color modulation across the visible light range. With the color change, each structural‐color pixel can be specifically encoded, allowing for this to encrypt dynamic information within the same pattern at different RHs. Furthermore, This study can precisely integrates tremendous different pixels and easily prepare various encrypted patterns, which guarantee the high‐capacity information input in a low‐cost way. Moreover, through computer programming and algorithm reading, the structural‐color patterns can be decoded and decrypted in real‐time, thus offering great potential for further encryption, anti‐counterfeiting, multiplexing encoding, and data storage. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical fundamentals, prerequisites for creation, and peculiarities of modeling a new method for determining the refractive index of biological tissues. The method uses a mirror ellipsoid of revolution as an optical element to ensure total internal reflection phenomena. This paper thoroughly analyzes the differences in the refractive index of healthy and pathological tissues on a biometric diagnostic basis. The analysis is used to model the measurement setup's parameters. This paper also considers various methods of determining the refractive index of biological tissues based on different principles of physical optics, such as interferometry, refractometry, ellipsometry, and goniophotometry. It systematizes typical optical elements of total internal reflection that can be used in goniophotometry. It justifies the selection of the element base for the goniometric installation based on the ellipsoidal reflector method. A simulation of the installation operation was carried out for various parameters of the ellipsoidal reflector, ensuring the measurement of the biological tissue refractive index from 1.33 to 1.7. This paper also proposes a constructive solution for manufacturing an ellipsoidal reflector of the required configuration. [ABSTRACT FROM AUTHOR]

Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve high precision. However, these configurations are complicated. Some measure the critical angle using simple structures, but their accuracy is unsatisfactory because it is difficult to judge the exact critical angle with intensity variations. Here, we propose several new schemes based on measuring the polarization change in the total internal reflection. The proposed method has the merits of simple structure and easy incident angle determination that gives the maximum phase change. Additionally, it is possible to find the material dispersion by measuring the wavelength dependence of the polarization ellipticity. Some useful formulas relating the refractive index to the maximum phase change are obtained. This work can provide valuable alternatives for refractive index measurement. [ABSTRACT FROM AUTHOR]

Almost no diffraction broadening of self-collimation beams and their easy crossing with low crosstalk offer new opportunities for acoustic wave manipulation. Here, we flexibly steer the self-collimation beam based on the total internal reflection of an airborne square lattice sonic crystal. The properly designed crystal/air interface may serve well as a total internal reflection mirror of the self-collimation beam, with which we are able to achieve the highly controllable beam reversal, snaking and crossing. Our scheme can be extended to more interesting beam steering, and have potential applications in constructing high-density integrated acoustic circuits. [ABSTRACT FROM AUTHOR]

The modulation of a terahertz (THz) wave on amplitude, phase and polarization is important for the application of THz technology, especially in the field of imaging, and is one of the current research hotspots. Silicon-based, optically excited THz modulator is a wavefront modulation technique with a simple, compact and reconfigurable optical path. It can realize the dynamic modulation of THz wavefronts by only changing the projected two-dimensional pattern, but it still suffers from the problems of lower modulation efficiency and slower modulation rates. In this article, the Drude model in combination with the multiple thin layers structure model and Fresnel matrix method is used to compare the modulation efficiencies of three modulation modes and more factors. The method is more accurate than the popular proposed method, especially when the thickness of the excited photoconductive layers reaches a few hundred microns. In comparing the three modes, namely transmission, ordinary reflection and total internal reflection, it is found the total internal reflection modulation mode has the best modulation efficiency. Further, under this mode, the effects of three factors, including the lifetime of photo-excited carriers, the wavelength of pump light and the frequency of THz wave, on the performance of THz modulator are analyzed. The simulation results show that the realization of total internal reflection using silicon prisms is a simple and effective method to improve the modulation efficiency of a silicon-based optically excited THz modulator, which provides references for the design of a photo-induced THz modulator. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical fundamentals, prerequisites for creation, and peculiarities of modeling a new method for determining the refractive index of biological tissues. The method uses a mirror ellipsoid of revolution as an optical element to ensure total internal reflection phenomena. This paper thoroughly analyzes the differences in the refractive index of healthy and pathological tissues on a biometric diagnostic basis. The analysis is used to model the measurement setup’s parameters. This paper also considers various methods of determining the refractive index of biological tissues based on different principles of physical optics, such as interferometry, refractometry, ellipsometry, and goniophotometry. It systematizes typical optical elements of total internal reflection that can be used in goniophotometry. It justifies the selection of the element base for the goniometric installation based on the ellipsoidal reflector method. A simulation of the installation operation was carried out for various parameters of the ellipsoidal reflector, ensuring the measurement of the biological tissue refractive index from 1.33 to 1.7. This paper also proposes a constructive solution for manufacturing an ellipsoidal reflector of the required configuration.

We have considered the refraction of surface electromagnetic waves (SEW) at the heterogeneous metasurface. The considered structure consists of three regions: mu-negative metamaterial, ordinary magnetic, and vacuum. The boundaries between considered media are planar. A phenomenological approach was used; media were assumed to be lossless and isotropic. In this paper, we show the possibility of total internal reflection effect for SEW of TE-polarization that can propagate along such heterogeneous metasurface. The value of the angle of total internal reflection decreases for higher frequency waves from the interval under consideration. The presented result may help design both research and industry complex systems.

Materials capable of dynamically and reversibly altering their emission are relevant for numerous optical applications. Here, the anisotropic morphology‐directed light emission from fluorescent Janus emulsion droplets, an intrinsically chemo‐responsive material platform, is investigated. Informed by experimental observations of morphology‐dependent optical confinement of internally emitted light within the higher refractive index phases, ray‐tracing is used to predict and fine‐tune the droplets' optical properties and their ability to concentrate light. Theoretical prediction and closely matching experimental results show that the collection of incident light and the confinement of emitted light in the internal droplet phase due to total internal reflection both contribute to the droplets' anisotropic light emission profile. A novel ratiometric dual‐angle fluorescence detection approach that exploits the gravitational alignment of the droplets is implemented to quantify the morphology‐dependent large‐scale chemically‐induced modulation of the anisotropic emission of droplet layers. Relevant emulsion design parameters are systematically examined to enhance the signal‐to‐noise ratio, and a second emitter is co‐compartmentalized inside the droplets to amplify the anisotropic light confinement via an absorption–emission cascade. Preferential excitation of dyes in proximity to the internal droplet interface enhances the collected light intensity, demonstrating that dye‐loaded Janus emulsion droplets function as stimuli‐responsive, tunable, fluorescent optical elements. [ABSTRACT FROM AUTHOR]

A theoretical study has been made of the reflection and refraction of a harmonic sound wave on the boundary "bubble liquid–porous medium saturated with bubble liquid." It has been established that in the case of incidence of such a wave on the indicated boundary at a certain angle, the total internal reflection of a transverse wave occurs. Conditions have been determined with which the reflection of the wave as that from a rigid wall occurs. [ABSTRACT FROM AUTHOR]

Optical fibres are generally used to provide a guided path to optical signals. Optical fibres are classified as multi-mode or single-mode fibres. Multi-mode graded index (GRIN) optical fibres have been prevalent in short-range optical networks, while single-mode GRIN fibres are used for long-range links. Another potential application of optical fibre is the optical delays in numerous applications, such as quantum computing, network buffering, data synchronization, pattern correlation, etc. This paper conceptualizes a novel application of an asymmetric GRIN optical fibre for possible enhanced optical delays. An asymmetric GRIN parabolic profile with helical structure geometry has been proposed for this task. A detailed analysis has been presented to investigate the effects of various parameters of the proposed geometry. Further, a guided propagation has also been demonstrated with the help of ray optics and the Helmholtz wave equation to assess the feasibility of the proposal. The presented investigations revealed that the geometrical length of the proposed structure is significantly compact compared with the traditional GRIN fibre, proving it beneficial for optical delays. [ABSTRACT FROM AUTHOR]

Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve high precision. However, these configurations are complicated. Some measure the critical angle using simple structures, but their accuracy is unsatisfactory because it is difficult to judge the exact critical angle with intensity variations. Here, we propose several new schemes based on measuring the polarization change in the total internal reflection. The proposed method has the merits of simple structure and easy incident angle determination that gives the maximum phase change. Additionally, it is possible to find the material dispersion by measuring the wavelength dependence of the polarization ellipticity. Some useful formulas relating the refractive index to the maximum phase change are obtained. This work can provide valuable alternatives for refractive index measurement.

Scattering is one of the main challenges in scaling up photocatalytic water splitting using the most prevalent powder catalysts. This can be overcome by decoupling the reaction medium from light transmission, as in the case of optical fibers. Here we explore utilizing optical fibers coated with 5 wt% CuO supported on TiO 2 for photocatlytic H 2 production from water-methanol mixtures. CuO/TiO 2 is a well studied photo catalyst in which photoreduced Cu species are known to act as sensitizers for inducing visible light activity. Lower activity of sequentially coated systems indicates that appropriate interfaces of active Cu and TiO 2 with water are desirable. The scalability of such optical fiber-based systems along with potential in non-potable turbid water media are demonstrated. Maximum activity of 22 μmoles of H 2 in 8 h was obtained with 50 mg of catalyst coated on optical fibers, which increases linearly with increase in fiber numbers, whereas, drastic reduction in activity is observed in powder catalyst upon increasing the catalyst quantity. A one-to-one comparison of 700 mg of catalyst in powder form and coated on optical fibers indicates more than one order enhancement in activity in the optical fiber based system. In addition, ∼70% retention in activity in highly turbid non-potable water was observed as compared to powdered system which shows complete reduction in the activity by 99.99%. • 5 wt%CuO/TiO 2 coated optical fiber bundles are studied for photocatalytic hydrogen evolution via water splitting. • Change in directionality of light reduces scattering issues observed in powder catalysts on scale up. • H 2 production can be increased by merely increasing number of optical fibers. • More than one order enhancement in activity in the optical fiber when compared to powder on scale up. • Retention of ∼70% activity in turbid non-potable water. [ABSTRACT FROM AUTHOR]

Predicting the dynamics of impacting drops is crucial in various industrial applications such as spray and inkjet technologies. Especially in painting technology, the entrapment of air bubbles greatly reduces the product quality. The formation of a thin air film in front of the moving contact line causes the entrapment of air bubbles in the spreading phase. To clarify the main forces acting at the gas-liquid interface that induce air bubbles entrapment, we investigate the contact line velocity of impacting drops by taking bottom view images using the total internal reflection (TIR) method. We used droplets of glycerol or glycerol-ethanol solutions and solid surfaces covered with either glycerol or silicone oil. Our results show the contact line velocity decreased rapidly at Tc when a thin air film was formed and settled down at a constant value Vconst after the formation of the air film. Furthermore, we revealed that drop viscosity affects Tc and Vconst . Moreover, we found that after Tc, the lubrication pressure of the air had the same order of magnitude as the viscous shear stress of the drop, which implied the importance of the air lubrication pressure. [ABSTRACT FROM AUTHOR]

In this work, we present the relative Fresnel (Goos-Hänchen) phase crossover between the total internal reflection and diffusion regimes by employing polarization tomography. This powerful technique not only enables us to access information about the amplitude and relative phase of the state for total reflection but also facilitates the identification of the transition between these regimes. In all cases, the experimental data are in very good agreement with the theoretical predictions. As an application, we propose the use of the GH phase to implement a phase gate, which is an essential requirement for universal computation. In this context, our system offers a more cost-effective and alternative set up to implement the phase gate and simulate compensator devices. [ABSTRACT FROM AUTHOR]

Featured Application: A new class of active topological photonic devices and laser arrays. A photonic topological insulator is a structure that isolates radiation in the bulk rather than at the edge (surface). Paradoxically, applications of such an insulator focus on its conducting edge states, which are robust against structural defects. We suggest a tiling photonic topological insulator constructed from identical prism resonators connected to each other. The light beam circulates inside the tiling bulk without propagation. However, we experimentally demonstrate a topologically-protected propagating state due to the disconnected faces of the edge resonators. The investigated state is robust against removing or attaching prism resonators. Moreover, the protection principle is phase-free and therefore highly scalable both in wavelength and resonator size. The tiling is suggested for active topological photonic devices and laser arrays. [ABSTRACT FROM AUTHOR]

The modulation of a terahertz (THz) wave on amplitude, phase and polarization is important for the application of THz technology, especially in the field of imaging, and is one of the current research hotspots. Silicon-based, optically excited THz modulator is a wavefront modulation technique with a simple, compact and reconfigurable optical path. It can realize the dynamic modulation of THz wavefronts by only changing the projected two-dimensional pattern, but it still suffers from the problems of lower modulation efficiency and slower modulation rates. In this article, the Drude model in combination with the multiple thin layers structure model and Fresnel matrix method is used to compare the modulation efficiencies of three modulation modes and more factors. The method is more accurate than the popular proposed method, especially when the thickness of the excited photoconductive layers reaches a few hundred microns. In comparing the three modes, namely transmission, ordinary reflection and total internal reflection, it is found the total internal reflection modulation mode has the best modulation efficiency. Further, under this mode, the effects of three factors, including the lifetime of photo-excited carriers, the wavelength of pump light and the frequency of THz wave, on the performance of THz modulator are analyzed. The simulation results show that the realization of total internal reflection using silicon prisms is a simple and effective method to improve the modulation efficiency of a silicon-based optically excited THz modulator, which provides references for the design of a photo-induced THz modulator.

In this paper, we review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency range. The particular focus of this review is on the possibility of homogeneous topological charge formation in the ultra-wide spectral interval inherent to ultrashort terahertz pulses. We review the available materials and components, analyse proposed and potentially possible solutions for broadband terahertz vortex and vector beam shaping, compare all developed approaches, and put forward a unified concept for constructing passive shapers of such beams from the existing component base.

In OLED, external light extraction shows very low efficiency due to total internal reflection, metal surface absorption and surface Plasmon coupling. The photonic crystal is a unique platform for controlling or modifying the light propagation and its properties such as transmission and absorption. The band structure of photonic crystal is mainly proposed for suppressing the spontaneous emission of light. In this work, the Finite Difference Time Domain (FDTD) mathematical modelling has been used to analyse the light extraction efficiency in the triangular band structure of OLED displays by measuring the Purcell factor. Due to the rectangular nature of FDTD solver region, it may be necessary to include multiple unit cells in the solver region for the triangular band structure. There is an improvement in the far-field intensity in OLED by optimizing the angular distribution of light through the substrate with the triangular band structure. Hence it can be widely used in ultra-compact optical devices. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance microscopy (SPRM) has been widely employed in biological fields because of its high spatial resolution and label-free detection modality. In this study, SPRM based on total internal reflection (TIR) is studied via a home-built SPRM system, and the principle of imaging of a single nanoparticle is analyzed as well. By designing a ring filter and combining it with the deconvolution algorithm in Fourier space, the parabolic tail of the nanoparticle image is removed, in which a spatial resolution of 248 nm is obtained. In addition, we also measured the specific binding between the human IgG antigen and goat anti-human IgG antibody using the TIR-based SPRM. The experimental results have proved that the system can image sparse nanoparticles and monitor biomolecular interactions. [ABSTRACT FROM AUTHOR]

In this paper, a novel optical measurement principle for deformation, especially torsion, is presented. A laser beam is guided via total internal reflection (TIR) in a prism rod. Every single reflection causes an increasing change in the beam path, which can be measured by its effect on the outcoupling position of the laser. With a diameter of the prism rod of 10   mm and a length of 120   mm , the system achieves torsion sensitivities between 350   µ m / ° and more than 7000   µ m / ° , depending on the actual torsion angle φ. A decency level of sensitivity is defined for comparison, which is exceeded by a factor of ~ 55 at φ = 0 . The presented principle of TIR prism rods can be adapted to measure different load cases. Using two laser beams, bending and torsion can be distinguished and combined load cases analyzed. The resulting system can be integrated into machine elements, such as screws, to perform condition monitoring on mechanically loaded components. [ABSTRACT FROM AUTHOR]

A photonic-crystal slab can support bound states in the continuum (BICs) that have infinite lifetimes but are embedded into the continuous spectrum of optical modes in free space. The formation of BICs requires a total internal reflection (TIR) condition at both interfaces between the slab and the free space. Here, we show that the TIR of Bloch waves can be directly obtained based on the generalized Fresnel equations proposed. If each of these Bloch waves picks up a phase with integer multiples of 2π for traveling a round trip, light can be perfectly guided in the slab, namely forming a BIC. A BIC solver with low computational complexity and fast convergence speed is developed, which can also work efficiently at high frequencies beyond the diffraction limit where multiple radiation channels exist. Two examples of multi-channel BICs are shown and their topological nature in momentum space is also revealed. Both can be attributed to the coincidence of the topological charges of far-field radiations from different radiation channels. The concept of the generalized TIR and the TIR-based BIC solver developed offer highly effective approaches for explorations of BICs that could have many potential applications in guided-wave optics and enhanced light–matter interactions. [ABSTRACT FROM AUTHOR]

An analysis of the ellipsometric parameters of the reflected light from the prism – test material – air system is carried out when circularly polarized light is incident on it under the conditions of the onset of the phenomenon of total internal reflection. At the onset of total internal reflection, the ellipsometry parameter Δ shows high variability with the angle of incidence, in contrast to the parameter r0. It is shown that TIR occurs when the angle of incidence is not equal to the critical angle of the adjacent media – for two different materials, these angles differ from each other. In the case of a film, the TIR phenomenon occurs at an angle equal to the critical angle at the prism-air interface and does not depend on the film material. The results obtained show the high efficiency of using the ellipsometric method together with circularly polarized incident radiation for diagnostics of thin films made of biological material.

Total internal reflection (TIR) is useful for interrogating physical and chemical processes that occur at the interface between two transparent media. Yet prism-coupled TIR imaging microscopes suffer from limited sensing areas due to the fact that the interface (the object plane) is not perpendicular to the optical axis of the microscope. In this paper, we show that an electrically tunable lens can be used to rapidly and reproducibly correct the focal length of an oblique-incidence scanning microscope (OI-RD) in a prism-coupled TIR geometry. We demonstrate the performance of such a correction by acquiring an image of a protein microarray over a scan area of 4 cm² with an effective resolution of less than 20 microns. The electronic focal length tuning eliminates the mechanical movement of the illumination lens in the scanning microscope and in turn the noise and background drift associated with the motion.

We present a concept that enables the determination of the complex refractive index of attenuating media from two critical angles, measured sequentially at two interfaces between a single sample and two different prisms. The proposed method is general in that it applies with s and p polarisation states, thus it is suited for the characterisation of isotropic as well as anisotropic media. Uncertainty analysis indicates that relative error in the determination of the real (imaginary) index can be less than 10 − 4 (in the order of 10 % ), respectively. [ABSTRACT FROM AUTHOR]

Solar technology candidates for building‐integrated photovoltaics and mobile power applications suffer from difficulty in fabricating large‐area, defect‐free solar cells, high materials costs, and small angular acceptance for incoming radiation. Solar concentrators collecting non‐normal‐incidence radiation and diffuse light while retaining high concentration ratios are therefore an enticing technology for high‐efficiency‐low‐cost photovoltaic systems. Here, a novel implementation of dielectric total internal reflection concentrators (DTIRCs) utilizing a piecewise smooth sidewall profile with an intermediate segment is developed. Coupled with a turning point in the entrance surface, this design allows for a tunable phase shift between the two sidewall segments, thereby allowing both the concentration ratio at normal incidence and the maximum acceptance angle to be increased, and the limit imposed by etendue conservation to be potentially exceeded under specific conditions. Scalable fabrication techniques are used to produce flexible DTIRCs, and their performance is verified with high‐efficiency commercial solar cells. Moreover, the collectible sun power over the course of a year is calculated, demonstrating that the new design receives more total power compared to traditional direct solar concentrators and standard DTIRC designs in realistic conditions, making it a good candidate for scalable micro‐concentrator systems that can be integrated directly into a solar cell package. [ABSTRACT FROM AUTHOR]

Heading toward the next‐generation versatile meta‐devices and meta‐systems with increasing complexity, it inevitably demands the cascading and coupling between multi‐layer metasurfaces to create new design space for meta‐optics. However, the accurate requirement for multilayer alignment at the nanoscale is significantly challenging due to the actual fabrication limitation, thus hindering the state‐of‐the‐art meta‐optics device integration and its practical application. Herein, a dynamic meta‐system for augmented reality (AR) holographic display functionality based on a layer‐folded metasurface integrated with an electrical‐driven liquid crystal (LC) platform is originally proposed and realized. By ingeniously folding the optical path between meta‐device vertical space, a beam‐steering metasurface in parallel with the other two holographic metasurfaces placed on a single surface is successfully cascaded. Such a layer‐folded scheme enjoys single‐time lithography processing for multi‐patterning with nanoscale alignment accuracy and avoids any vertical alignment issue. Furthermore, by combining with an electrical‐driven LC tuning scheme, the integrated meta‐system could actively switch independent‐encoded holographic images in real‐time floating in the actual‐world scene. Overall, it is envisioned that such a compact dynamic meta‐system suggests a feasible route for dynamic tunable wearable AR displays, intelligent dynamic displays, multi‐functional devices, etc. [ABSTRACT FROM AUTHOR]

When developing oil fields, there is an urgent task to quickly determine the type of pumped formation fluid, which includes formation gas, formation oil and formation water. In this paper, we propose a new type of a sensor element designed for flow refractometry of formation fluid based on the effect of total internal reflection. The sensor element is a taper tip of a conical shape made of sapphire and is 20 mm in length and 20 mm in diameter. The original shape of the sensor element is determined by a modified ray tracing method, taking into account analytical relations that determine the conditions for providing a larger dynamic range of measurements under specified physical, technological and design constraints. The conversion dependence of the tip is obtained for the wavelengths of 405 nm, 1064 nm and 3300 nm and allows determining the type of formation fluid (gas/water/oil). The proposed method enables the development of conical sensor elements based on the total internal reflection for downhole monitoring systems and optical threshold sensors of the refractive index.

A photonic topological insulator is a structure that isolates radiation in the bulk rather than at the edge (surface). Paradoxically, applications of such an insulator focus on its conducting edge states, which are robust against structural defects. We suggest a tiling photonic topological insulator constructed from identical prism resonators connected to each other. The light beam circulates inside the tiling bulk without propagation. However, we experimentally demonstrate a topologically-protected propagating state due to the disconnected faces of the edge resonators. The investigated state is robust against removing or attaching prism resonators. Moreover, the protection principle is phase-free and therefore highly scalable both in wavelength and resonator size. The tiling is suggested for active topological photonic devices and laser arrays.

One of the main issues in integrated photonics is the coupling of free‐space or optical fiber radiation to waveguides on the photonic chip surface. The ideal coupler is miniature, highly efficient, and provides a large number of addressable devices. Here, a new concept of 3D out‐of‐plane coupler is introduced, which is a microscale prism exploiting frustrated total internal reflection in the Otto configuration to excite surface electromagnetic waves or near‐surface waveguide modes. A method for designing the couplers operating at normal incidence is proposed and it is applied to excite Bloch surface waves (BSWs) in 1D photonic crystals. Polymer microprisms are printed using two‐photon laser lithography and allow transferring more than 40% of the incident light energy into BSWs. The couplers enable focusing BSWs simultaneously with their excitation. Advanced design prisms can provide nearly 100% efficiency, making the proposed concept an alternative to actual coupling concepts in integrated photonics. [ABSTRACT FROM AUTHOR]

Featured Application: Interfacial sensors or light modulators made of transparent dielectric materials alone. A simple scheme for single-channel coherent perfect absorption (CPA) of transparent materials is proposed and experimentally realized using total internal reflection by grazing incidence, with a single dielectric layer sandwiched by semi-infinite dielectric layers. In a 1.48-µm thick polyvinylpyrrolidone (PVP) film, dip-coated on a MgF2 substrate both transparent in the visible, reflectance dips due to nearly 90% absorption by single-channel CPA were observed in the wavelength range of 370–800 nm, with white light from a Xe lamp incident on the side face of the substrate and extracted from the other side through multiple reflections in the PVP layer. This is a simple and inexpensive CPA scheme, and it is expected to have various applications by changing the substrate/polymer material or dispersing molecules in the polymer film. This paper also provides a design guideline for grazing-incidence waveguide-mode sensors using transparent dielectric materials. [ABSTRACT FROM AUTHOR]

The demand for extra-thin, large-area, and high-luminance flat-panel displays continues to grow, especially for portable displays such as gaming laptops and automotive displays. In this paper, we propose a design that includes a light guide layer with a microstructure above the mini-light-emitting diode light board. The light control microstructure of concave parabel-surface microlens arrays on a light-emitting surface increases the likelihood of total internal reflection occurring and improved the uniformity merit function. We used a 17 in prototype with quantum-dot and optical films to conduct our experiments, which revealed that the thickness of the module was only 1.98 mm. When the input power was 28.34 watts, the uniformity, average luminance, and CIE 1931 color space NTSC of the prototype reached 85%, 17,574 cd/m2, and 105.37%, respectively. This module provided a flat light source that was extra thin and had high luminance and uniformity. [ABSTRACT FROM AUTHOR]