Transmission Of Near-infrared Light Research Articles

Reprogrammable metasurface design for NIR beam steering and active filtering

Reprogrammable metasurfaces enable active modulation of light at subwavelength scales. Operating in the microwave, terahertz, and mid-infrared ranges, these metasurfaces find applications in communications, sensing, and imaging. Electrically tunable metasurfaces operating in the near-infrared (NIR) range are crucial for light detection and ranging (LiDAR) applications. Achieving a NIR reprogrammable metasurface requires individual gating of nano-antennas, emphasizing effective heat management to preserve device performance. To this end, here we propose an electrically tunable Au–vanadium dioxide (VO2) metasurface design on top of a one-dimensional Si–Al2O3 photonic crystal (PC), positioned on a SiC substrate. Each individual Au–VO2 nano-antenna is switched from an Off to ON state via Joule heating, enabling the programming of the metasurface using 1-bit (binary) control. While operating as a nearly perfect reflector at λ0=1.55μm , the materials, thickness, and number of the layers in the PC are carefully chosen to ensure it acts as a thermal metamaterial. Moreover, with high optical efficiency (R ∼ 40% at λ0 ), appropriate thermal performance, and feasibility, the metasurface also enables broadband programmable beam steering in the 1.4−1.7μm range for a wide steering angle range. This metasurface design also offers active control over NIR light transmittance, reflectance and absorptance in the wavelength range of 0.75−3μm . These characteristics render the device practical for LiDAR and active filtering.

2D ordered porous VO2-based composite film with enhanced thermochromism performance and high stability for smart windows

Thermochromic vanadium dioxide (VO2) can autonomously adjust near-infrared light transmittance in response to the external temperature changes, offering a significant reduction in building energy consumption when applied it in smart window. However, it is a big challenge for simultaneous optimization of visible light transmittance, solar modulation ability, and stability in VO2. To address such a big challenge, this study successfully prepared a 2D ordered porous VO2@Zn3V3O8 composite film. The as-obtained film exhibits exceptional optical performance with a visible light transmittance (Tlum) of 62.75 % and the solar modulation ability (ΔTsol) of 10.62 %, based on the anti-reflective effects of porous structure and the localized surface plasma resonance (LSPR) absorption of independently distributed VO2 nanoparticles. In addition, the composite structural film showcases excellent environmental durability that 80 % of ΔTsol could be retained after 30 days aging under the conditions of 50 % humidity and 100 °C. This work propels the practical application of VO2 smart windows and offers valuable insights for the design of composite structures.

Comparative analysis of NIR point source and surface array probes in two-phase flow measurement model

As one of the most significant parameters, phase fraction is of great importance for ensuring the accuracy of two-phase flow measurement. Although near-infrared (NIR) technology has been widely used, its accuracy remains limited. Two methods have been proposed to reduce the energy loss of near-infrared light transmission signal in two-phase flow: the point light source method, which shortens optical path and the array light source method for increasing light source area. Experiments were conducted on single phase flow and gas–liquid two-phase flow, and the results indicated that the signal transmission effect of the point source near-infrared device was better. Using the experimental results from the point source near-infrared device, phase fraction models for bubble flow, annular flow, and slug flow were established. Validation results demonstrate that the relative measurement error of the three phase fraction models is within ± 4.96 %.

A Smart Window with Passive Radiative Cooling and Switchable Near-Infrared Light Transmittance via Molecular Engineering.

Smart windows with synergetic light modulation have heightened demands for applications in smart cars and novel buildings. However, improving the on-demand energy-saving efficiency is quite challenging due to the difficulty of modulating sunlight with a broad bandwidth in an energy-saving way. Herein, a smart window with switchable near-infrared light transmittance and passive radiative cooling is prepared via a monomer design strategy and photoinduced polymerization. The effects of hydrogen bonds and fluorine groups in acrylate monomers on the electro-optical properties as well as microstructures of polymer-dispersed liquid crystal films have been systematically studied. Some films show a high contrast ratio of 90.4 or a low threshold voltage (Vth) of 2.0 V, which can be roll-to-roll processed in a large area. Besides, the film has a superior indoor temperature regulation ability due to its passive radiative cooling and controllable near-infrared light transmittance properties. Its radiative cooling efficiency is calculated to be 142.69 W/m2 and NIR transmittance could be switched to below 10%. The introduction of a carboxylic monomer and fluorinated monomer into the system endows the film with a highly efficient temperature management capability. The film has great potential for applications in fields such as flexible smart windows, camouflage materials, and so on.

Oxygen-deficient tungsten oxide nanoflowers for dynamically tunable near-infrared light transmittance of smart windows

Oxygen-deficient tungsten oxide nanoflowers for dynamically tunable near-infrared light transmittance of smart windows

New energy-saving building developed by using polyethylene glycol/halloysite nanotube energy-storage blanket and heat-insulating glass with NaxWO3@SiO2 nano-coating

Transparent heat-insulation glass (HIG) with a highly selective light-absorbing coating and an energy-storage blanket (ESB) loaded with phase change materials show considerable potential in reducing building energy consumption. However, the energy-saving effect of a single material is usually not ideal, and the instability of HIG and ESB limits their applications. In this work, HIG with enhanced stability and a form-stable ESB was prepared. The temperature difference between various indoor areas and energy consumption were reduced simultaneously because of the temperature regulation function of the HIG and ESB in the light and dark areas. NaxWO3@SiO2-coated HIG showed excellent daylighting and near-infrared-light-shielding ability with visible light transmittance of 71% and near-infrared light transmittance of 16%, respectively. Moreover, polyethylene glycol/halloysite nanotube composite phase change material with a high enthalpy of 71.1 J/g and a suitable phase change temperature of 27.5 °C was prepared for the form-stable ESB. The test room experiment indicated that the combination of the HIG and ESB (HIG–ESB) reduced the indoor temperature difference from 6.8 °C to 0.9 °C and the maximum temperature by 33–40%. The energy consumption simulation revealed that the ESB can save energy in all selected cities, whereas HIG is only applicable to cities in warm regions. HIG–ESB achieved the highest annual energy-saving rate of 43.9% in Hong Kong. The joint application of the HIG and ESB provides a new strategy for developing passive energy-saving buildings.

Inside-the-body light delivery system using endovascular therapy-based light illumination technology.

Light-based therapies are promising for treating diseases including cancer, hereditary conditions, and protein-related disorders. However, systems, methods, and devices that deliver light deep inside the body are limited. This study aimed to develop an endovascular therapy-based light illumination technology (ET-BLIT), capable of providing deep light irradiation within the body. The ET-BLIT system consists of a catheter with a single lumen as a guidewire and diffuser, with a transparent section at the distal end for thermocouple head attachment. The optical light diffuser alters the emission direction laterally, according to the optical fibre's nose-shape angle. If necessary, after delivering the catheter to the target position in the vessel, the diffuser is inserted into the catheter and placed in the transparent section in the direction of the target lesion. ET-BLIT was tested in an animal model. The 690-nm near-infrared (NIR) light penetrated the walls of blood vessels to reach the liver and kidneys without causing temperature increase, vessel damage, or blood component alterations. NIR light transmittance from the diffuser to the detector within the organ or vessel was approximately 30% and 65% for the renal and hepatic arteries, respectively. ET-BLIT can be potentially used in clinical photo-based medicine, as a far-out technology. ET-BLIT uses a familiar method that can access the whole body, as the basic procedure is comparable to that of endovascular therapy in terms of sequence and technique. Therefore, the use of the ET-BLIT system is promising for many light-based therapies that are currently in the research phase. Supported by Programme for Developing Next-generation Researchers (Japan Science and Technology Agency); JSPS KAKENHI (18K15923, 21K07217); JST-CREST (JPMJCR19H2); JST-FOREST-Souhatsu (JPMJFR2017); The Uehara Memorial Foundation; Yasuda Memorial Medical Foundation; Mochida Memorial Foundation for Medical and Pharmaceutical Research; Takeda Science Foundation; The Japan Health Foundation; Takahashi Industrial and Economic Research Foundation; AICHI Health Promotion Foundation; and Princess Takamatsu Cancer Research Fund.

Ultra-broadband near infrared phosphor with wide spectral range and long peak wavelength achieved by double-site occupation

The miniaturization and intelligence of near infrared (NIR) devices urgently require an excellent broadband NIR phosphor. However, emission spectra of most NIR phosphors cover less than 1200 nm with a full width at half maximum (FWHM) less than 200 nm and a peak wavelength less than 900 nm. Here, we successfully developed ultra-broadband NIR phosphors ScNbO4:Cr3+ which can overcome the above shortcomings based on a double-site occupancy strategy. The phosphors achieve ultra-broadband NIR emission from 800 to 1400 nm with a peak wavelength at 980 nm. Its FWHM is up to 217 nm. The valence state of Cr ions in phosphors was analyzed. The double-site occupancy of Cr3+ ions in the host and the relationship between host structure and optical properties are discussed in detail. NIR light transmission experiments show that phosphors have potential application value in non-destructive analysis. This work develops an excellent NIR luminescent material and provides an efficient method to obtain ultra-broadband NIR phosphors with longer peak wavelength.

Vanadium-doped indium tin oxide window layer in Sb2Se3 solar cell

Antimony selenide (Sb2Se3) is an emerging photovoltaic material. Indium tin oxide (ITO) is commonly used as the window layer material in Sb2Se3 solar cells; however, ITO films have poor absorption in the near-infrared spectrum. Our objective in this research was to replace conventional ITO with vanadium-doped indium tin oxide (ITO:V) to improve the near-infrared light transmittance of Sb2Se3 thin film solar cells and thereby enhance the efficiency of solar cells. The experiment parameters included vanadium doping concentration and annealing temperature. ITO films doped with 0.35 at.% V and annealed at 100 °C for 30 min outperformed conventional ITO films in terms of photovoltaic performance. The proposed scheme improved light transmittance from 80.03% to 83.02% over a wavelength range of 400–1100 nm, which led to a significant improvement in Jsc and device efficiency (from 4.5% to 5.6%). It appears that ITO films can be doped with vanadium to improve transmittance by reducing refractive index degradation in the near-infrared region.

Enhanced dual-band modulation of visible and near-infrared light transmittance in electrochromic composite films based on Preyssler-type polyoxometalates and W18O49

Benefitting from a unique wrap-type porous nano-structure, a POM/W18O49 composite film achieved excellent electrochromic properties and a high coloration efficiency, and is promising for applications in smart windows.

Shape-programmable fluid bubbles for responsive building skins

Building facades that can dynamically absorb light in the visible and near-infrared region of the electromagnetic spectrum enable temporally-programmable optical control and improved building energy-efficiency. Conventional solid-phase chromogenic materials suffer performance limitations that might be addressed by highly-mobile, self-assembling, gas- and liquid-phase alternatives. Here, we introduce a fluidic interface for buildings that can achieve light modulation through reversible injections of air bubbles with self-organizing morphologies. We establish criteria for injection-rate- and flow-field-dependent bubble shape. And we demonstrate experimental control over visible light transmission, near-infrared light transmission, solar heat gain, and indoor temperature, through active modulation of bubble size. Energy models help predict the comparative operational performance of our system, allowing us to couple motion-sensing capabilities with digitally-actuated bubble formation, towards demonstrating the potential for a tunable fluidic mechanism in responsive building design.

Direct Near Infrared Light-Activatable Phthalocyanine Catalysts.

The high penetration of near-infrared (NIR) light makes it effective for use in selective reactions under light-shielded conditions, such as in sealed reactors and deep tissues. Herein, we report the development of phthalocyanine catalysts directly activated by NIR light to transform small organic molecules. The desired photocatalytic properties were achieved in the phthalocyanines by introducing the appropriate peripheral substituents and central metal. These phthalocyanine photocatalysts promote cross-dehydrogenative-coupling (CDC) under irradiation with 810 nm NIR light. The choice of solvent is important, and a mixture of a reaction-accelerating (pyridine) and -decelerating (methanol) solvents was particularly effective. Moreover, we demonstrate photoreactions under visible-light-shielded conditions through the transmission of NIR light. A combined experimental and computational mechanistic analysis revealed that this NIR reaction does not involve a photoredox-type mechanism with electron transfer, but instead a singlet-oxygen-mediated mechanism with energy transfer.

Near‐Infrared Multilayer MoS2 Photoconductivity‐Enabled Ultrasensitive Homogeneous Plasmonic Colorimetric Biosensing (Adv. Mater. Interfaces 24/2021)

Plasmonic Colorimetric Biosensing of Proteins in Biofluids In article number 2101291, Younggeun Park, Xiaogan Liang, Katsuo Kurabayashi, and co-workers demonstrate rapid, “mix-and-read” detection of cancer marker proteins at sub-femtomolar concentrations in unprocessed whole blood using a multilayered molybdenum disulfide photoconductive channel and plasmonic nanoparticles. Minimized carrier scattering within the photoconductive channel allows for detecting subtle near-infrared light transmission shifts accompanying antigen-induced plasmonic nanoparticle aggregation in blood.

Sodium tungsten bronze (NaxWO3)-doped near-infrared-shielding bulk glasses for energy-saving applications

Tungsten bronze coatings and films have attracted global attention for their applications in near-infrared (NIR)-shielding windows. However, they are unstable in strong ultraviolet, humid heat, alkaline and/or oxidizing environments and are difficult to be coated on glass surfaces with complex shape. Here, we address these limitations by doping sodium tungsten bronze (NaxWO3) into bulk glasses using a simple glass melting method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, TEM and SEM-EDS characterization confirmed the presence of sodium tungsten bronze (NaxWO3) functional units inside the 34SiO2-38B2O3-28NaF glass matrix. Because the functional units are well protected by the glass matrix, the fabricated glasses are stable under hot, humid, oxidizing conditions, as well as under ambient conditions, with no change after 360 days. The NIR-shielding performance of these glasses can be adjusted to as high as 100 % by varying WOx concentration (2−8 mol%) and quenching temperature (1000−1400 °C). With a content of 6 mol% WOx and a quenching temperature of 1000 °C, the bulk glass shows 63 % transmission of visible light and only 11 % transmission of NIR light at 1100 nm. Thermal insulation experiments show that the NIR-shielding performance of the glasses are far superior to commercial soda lime window glass or indium-doped tin oxide (ITO) glass, and comparable to cesium tungsten bronze coated glass. The novel bulk glasses have higher stability, simpler processing, and can be easily made into complex shapes, making them excellent alternative materials for energy-saving glasses.

FVSR-Net: an end-to-end Finger Vein Image Scattering Removal Network

Based on the ever-growing emphasis on high security of biometrics recognition, finger vein recognition has captured more and more attention. However, due to the light scattering in human skin tissue during near-infrared light transmission imaging, the collected finger vein images are always degraded dramatically, which leads to the unreliability of vein features and the low accuracy of finger vein recognition. Although considerable traditional methods are dedicated to eliminating the effect of light scattering on imaging, the clearer images cannot be output end-to-end, the processes of restoring degraded finger vein images are laborious as well. Thereupon, with the aim at improving the visibility of finger vein features and generating clear finger vein images end-to-end, this effort represents a simple and effective method utilizing Convolutional Neural Network (CNN). First, in our previous work, the biological optical model used to settle the matter of skin scattering is modified to output restored finger vein images in an end-to-end manner. Second, a multi-scale CNN named E-Net is established to acquire credible estimation map of finger vein features, which is conducive to the acquisition of pleasurable restoration outcome. Finally, a scattering removal framework, addressed as Finger Vein Image Scattering Removal Network (FVSR-Net), is designed via integrating improved biological optical model with E-Net. Such a novel design facilitates the generation of clearer venous regions and increases computational efficiency and stability. Experiments accomplished on two finger vein datasets demonstrate the superiority of our proposed method in terms of visual quality and recognition performance.

Regulating the Structural, Transmittance, Ferroelectric, and Energy Storage Properties of K0.5Na0.5NbO3 Ceramics Using Sr(Yb0.5Nb0.5)O3

Lead-free (1 − x)K0.5Na0.5NbO3–xSr(Yb0.5Nb0.5)O3 (KNN–xSYbN, x = 0.15, 0.175, 0.20, 0.225, 0.25, 0.30) ceramics have been fabricated using the traditional solid-phase sintering method. The effects of Sr(Yb0.5Nb0.5)O3 doping on the microstructure, phase transition, and optical and electrical properties were investigated in detail. X-ray diffraction analysis revealed that the ceramics had pseudocubic phase structure. At x = 0.175, the near-infrared light transmittance of the ceramic reached 43.5% and the optical bandgap Eg was 2.89 eV. After introduction of Sr(Yb0.5Nb0.5)O3, the crystal grains of the ceramic became fine dense small cubes. Excessive doping (x ≥ 0.20) reduced the density of the ceramic and melted the ceramic surface. The ceramic with x = 0.175 exhibited optimized energy storage properties with Wrec = 0.21 J/cm3 and η = 78.2%. The maximum dielectric constant of 1867.9 was obtained at x = 0.175, and its Tm peaks shifted toward lower temperature. The good insulation performance of the ceramics was confirmed by impedance spectroscopy.

Abstract A15: Prenatal exposure to polycyclic aromatic hydrocarbons and breast tissue composition in adolescent girls

Abstract Polycyclic aromatic hydrocarbons (PAH) are common environmental pollutants that result from incomplete combustion of biomass and fossil fuels. PAH have endocrine-disrupting properties and are known animal carcinogens. Evidence from case-control studies suggests an association between PAH and breast cancer risk, but longitudinal research on PAH exposure during critical windows of susceptibility, such as prenatally and in early life, is limited. The purpose of this study was to prospectively examine whether prenatal exposure to PAH is associated with breast tissue composition, an intermediate marker of breast cancer risk, in adolescent girls. We studied 105 adolescent girls in the Columbia Center for Children’s Environmental Health (CCCEH) birth cohort, which recruited nonsmoking African American and Dominican American pregnant women living in three low-income neighborhoods in New York City from 1998-2006. Women wore a small backpack holding a personal air monitor for 2 consecutive days during the 3rd trimester of pregnancy, which measured concentrations of pyrene and 8 other carcinogenic PAH (summed and categorized into tertiles for analysis). Girls completed a follow-up clinic visit in adolescence (ages 11.2-19.6 years, median=15.8), at which time breast tissue composition was measured by optical spectroscopy (OS). OS is a novel and noninvasive tool that provides a broad compositional view of the breast by capturing variation in the amount of water, lipid, oxy-hemoglobin, deoxy-hemoglobin, and collagen, as well as overall cellular and connective tissue density. OS measured red and near-infrared light transmission of 7 wavelengths (650-1060 nm) at 4 source-detector distances in each breast quadrant, resulting in 16 overlapping tissue volumes. Principal component analysis was used to reduce spectral data and generate principal component (PC) scores for each participant, which were averaged over both breasts. We used multivariable linear regression to examine associations of prenatal PAH measures (pyrene and Σ8 PAH) with each of the first 4 OS PCs, which explained >99% of the spectral variation in the sample. Models were adjusted for age, ethnicity, body mass index (BMI) at time of OS measurement, age at breast development, and mothers’ prepregnancy BMI. After adjusting for covariates, PC1 scores were significantly lower on average in the highest compared to lowest tertile of prenatal ambient Σ8 PAH (β = -0.42, 95% CI = -0.81 to -0.02, p = 0.04). PC1 covered 91.8% of the spectral variations and represents overall light attenuation from higher scattering due to higher cellularity and connective tissues. PC1 also mapped to multiple chromophores including hemoglobin and collagen. No associations were found between prenatal ambient Σ8 PAH and PCs 2-4, and no associations with OS PCs were found for pyrene. To conclude, we found evidence suggesting that prenatal exposure to PAH is associated with breast tissue composition in adolescent girls. Citation Format: Rebecca D. Kehm, Lothar Lilge, E. Jane Walter, Nur Zeinomar, Jasmine A. McDonald, Parisa Tehranifar, Julie B. Herbstman, Rachel L. Miller, Mary Beth Terry. Prenatal exposure to polycyclic aromatic hydrocarbons and breast tissue composition in adolescent girls [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A15.

Solvothermal Synthesis and Near-Infrared Shielding Properties of Cs0.3WO3/WO3Composites

The Cs[Formula: see text]WO3/WO3composite with near-infrared shielding properties was synthesized by the solvothermal method using tungstic acid and cesium salt as raw materials. The as-prepared composites were tested by X-ray powder diffraction, scanning electron microscopy, energy spectrum analysis, transmission electron microscopy, electron energy loss spectroscopy, and ultraviolet-visible near-infrared spectroscopy. The effects of different reaction conditions on the structure and near-infrared shielding properties of the synthesized composites were investigated. The best near-infrared light transmittance of as-prepared composites can reach up to 9%, which provides a feasible solution for the near-infrared shielding material. The new homogeneous composites of cesium tungsten bronze and tungsten oxide are good candidates for solar filters.

Dual-response and Li+-insertion induced phase transition of VO2-based smart windows for selective visible and near-infrared light transmittance modulation

Chromogenic materials are widely used in the field of smart window with controllable throughput of solar energy and visible light. However, single modulation mode is often difficult to meet practical applications. Herein, we construct a novel multilayer device by effectively integrating thermochromic (TC) and electrochromic (EC) materials to selectively modulate visible and near-infrared (NIR) transmittance. The all-solid-state VO2-based multilayer device consists of VO2/LiTaO3/WO3 sandwich structure, with transparent conductor FTO and ITO as bottom electrode and top electrode, respectively. Therefore, this five-layer structure realized four reversible optical states, that is, TC layer passively responds to environmental temperature, while EC layer actively responds to external voltage simultaneously. Moreover, reversible migration of Li+ within the lattice of VO2 is achieved with a low voltage (just 3 V bias), which has an obvious effect (over 10 °C) on its phase change temperature (PCT). Finally, this novel dual-response VO2-based multilayer device provide a new strategy for VO2-based smart window applications.

Multispectral bioluminescence tomography-based general iterative shrinkage and threshold algorithm

Bioluminescence tomography (BLT) is a noninvasive optical molecular imaging modality with high sensitivity. The complexity of near-infrared light transmission in biological tissues and the limitation of measurable information place a higher demand on BLT source reconstruction algorithms. In this paper, we present a reconstruction algorithm based on general iterative shrinkage and threshold (GIST), which uses a non-convex smoothly clipped absolute deviation function as the penalty term, and solves a proximal operator problem that has a closed-form solution for the penalty. In addition, we utilize multispectral measurements and an iteratively shrinking permissible region strategy to address the ill-posedness of the BLT inverse problem. To investigate the source location and multi-source resolution abilities of the proposed method, we perform comparisons between three typical sparse reconstruction algorithms based on several groups of simulations and phantom experiments. The reconstruction results demonstrate great advantages of the proposed GIST algorithm in terms of source location accuracy in all considered source settings with different source depths and separations.