Search Results (46)

This study investigates a laser ranging technology scheme featuring a large divergence angle for both the emitted and received laser beams, focusing on applications where both the measured target and the ranging carrier are high-mobility platforms. A dual-concave beam-reducing lens design is adopted to reshape the original beam divergence angle of 10 mrad from the erbium glass laser into a ranging output beam divergence angle of 26 mrad, while maintaining the Gaussian energy distribution of the original laser beam. A φ500 μm photosensitive surface APD detector is used, and a combination of aspherical and spherical elements is employed in the receiving optical system to achieve a 30 mrad large field-of-view echo reception within the small photosensitive surface. This laser ranging system addresses the challenge of aiming and tracking for laser ranging between relatively high-speed moving objects and reduces the stability precision requirements for the ranging carrier platform. Full article

Phenothiazine-based photosensitizers bear the intrinsic potential to substitute various expensive organometallic dyes owing to the strong electron-donating nature of the former. If coupled with a strong acceptor unit and the length of N-alkyl chain is appropriately chosen, they can easily produce high efficiency levels in dye-sensitized solar cells. Here, three novel D-A dyes containing 1H-tetrazole-5-acrylic acid as an acceptor were synthesized by varying the N-alkyl chain length at its phenothiazine core and were exploited in dye-sensitized solar cells. Differential scanning calorimetry showed that the synthesized phenothiazine derivatives exhibited behavior characteristic of molecular glasses, with glass transition and melting temperatures in the range of 42–91 and 165–198 °C, respectively. Based on cyclic and differential pulse voltammetry measurements, it was evident that their lowest unoccupied molecular orbital (LUMO) (−3.01–−3.14 eV) and highest occupied molecular orbital (HOMO) (−5.28–−5.33 eV) values were fitted to the TiO₂ conduction band and the redox energy of I⁻/I₃⁻ in electrolyte, respectively. The experimental results were supported by density functional theory, which was also utilized for estimation of the adsorption energy of the dyes on the TiO₂ and its size. Finally, the compounds were tested in dye-sensitized solar cells, which were characterized based on current–voltage measurements. Additionally, for the compound giving the best photovoltaic response, the efficiency of the DSSCs was optimized by a photoanode modification involving the use of cosensitization and coadsorption approaches and the introduction of a blocking layer. Subsequently, two types of tandem dye-sensitized solar cells were constructed, which resulted in an increase in photovoltaic efficiency to 6.37%, as compared to DSSCs before modifications, with a power conversion value of 2.50%. Full article

The paper presents the results of developing Er-doped optical fibers for creating random single-frequency lasers in the wavelength range of 1570–1610 nm. The possibility of broadening the luminescence band of Er³⁺ ions in silicate glasses in the long-wavelength region of the spectrum by introducing a high concentration of P₂O₅, as well as by additional doping with Sb₂O₃, is investigated. It is found that both approaches do not improve the dynamics of luminescence decay in the L-band. In addition, Er₂O₃-GeO₂-Al₂O₃-SiO₂ and Er₂O₃-GeO₂-Al₂O₃-P₂O₅-SiO₂ glasses were studied as the core material for L-band optical fibers. The developed fibers exhibited high photosensitivity and a high gain of 5 and 7.2 dB/m, respectively. In these fibers, homogeneous arrays of extended weakly reflecting Bragg gratings were recorded directly during the fiber drawing process. Samples of arrays 5 m long and with a narrow reflection maximum at ~1590 nm were used as the base for laser resonators. Narrow-band random laser generation in the wavelength region of 1590 nm was recorded for the first time. At a temperature of 295 K, the laser mode was strictly continuous wave and stable in terms of output power. The maximal power exceeded 16 mW with an efficiency of 16%. Full article

This study examined spectroscopic, thermal, and other qualities, such as the lasing parameters, of Sm³⁺-doped glass with the composition 40P₂O₅–30ZnO–20LiCl–10BaF₂. The ellipsometric data were used in a Sellmeier dispersion relation to estimate the refractive index values of the glasses investigated. The measured absorption spectra of the doped glass reveal the presence of various absorption bands assigned to transitions from the ⁶H_5/2 ground state attributed to Sm³⁺-ion-excited states. We studied the decay of the ⁴G_5/2 level of the Sm³⁺ ions in the doped glass by analyzing its absorption and emission fluorescence spectra. The Judd–Ofelt hypothesis allowed us to determine that the quantum efficiency of the ⁴G_5/2–⁶H_7/2 transition is high: 96% and 97% for glass doped with 4.05 $\times$ 10¹⁹ ions/cm⁻³ and 11 $\times$ 10¹⁹ ions/cm⁻³, respectively. Furthermore, this glass exhibits efficient red/orange enhanced spontaneous emission that matches the excitation band of the photosensitizer material used in medical applications. Full article

Negative-tone photosensitive polyimides (PSPIs) with a low coefficient of thermal expansion (CTE) were prepared by dissolving polyimide precursor-poly(amide ester) (PAE) resins, photoinitiators, photocrosslinkers and other additives in organic solvents. Using triamine as a monomer and dianhydride and diamine as polycondensates, tri-branched structure PAE resins with different molecular weights named PAE-1~5 were prepared. A series of corresponding PSPI films named PSPI-1~5 were prepared from PAE-1~5 resins with the same formulation, respectively. The PSPI-1~5 films prepared from resins of this structure have excellent mechanical, thermal and electrical properties after being thermally cured at 350 °C/2 h in nitrogen. The PSPI-1~5 films’ coating solution also show good photolithographic performance and are able to obtain photolithographic patterns with a resolution of about 10 μm after homogenization, exposure and development. Among the PSPI-1~5 films, PSPI-2 has the most excellent lithographic properties with a weight average molecular weight (M_w) of 2.9 × 10⁴ g/mol, a CTE of 41 ppk/°C, a glass transition temperature (T_g) of 343 °C and a 5% weight loss temperature (T_d5) of 520 °C, making it suitable for industrial scale-up. The mechanical properties of elongation at breakage of 42.4%, tensile moduli of 3.4 GPa and tensile strength of 153.7 MPa were also measured. Full article

Dye-sensitized solar cells (DSSCs) can be used as greenhouse glazing materials in agrivoltaic systems because they are translucent, have different colors, and can produce electricity. However, the light quality of DSSCs differs from that of sunlight, and the visible light transmittance is low. Therefore, we compared the plant shape, growth, and leaf color of coleus, a highly photosensitive plant, under transparent glass and red-colored DSSCs. Coleus ‘Highway Rose’ was grown in transparent (T, the control), shaded (S), and DSSC (D) chambers maintained at 23 ± 2 °C. The DSSC chambers were additionally illuminated with blue (B), green (G), white (W), B+G, and R+B+W light-emitting diodes (LEDs) (D+L) at 60 μmol·m⁻²·s⁻¹ photosynthetic photon flux density for 15 h from 05:00 to 20:00. The coleus generally exhibited good growth under the T treatment. However, the light quality of DSSCs differed from that of sunlight, and the visible light transmittance decreased. Coleus exhibited increased growth and leaf color characteristics under the supplemental B lighting treatments (D+L_(RBW), D+L_(B), D+L_(BG), and D+L_(W)). Supplemental lighting with B LEDs using DSSCs improved plant morphology growth and leaf color. On the other hand, supplemental G lighting reinforced the shade avoidance syndrome. Moreover, DSSCs could aid in reducing the energy required to control the environment. Full article

Herein, we evaluate the conversion efficiency of dye-sensitized solar cells (DSSCs) photosensitized using two different natural dyes extracted from Alpinia purpurata and Alstroemeria flower petals. The appreciable absorption capacity of the extracts in the visible light region was examined through absorption spectroscopy. The functional groups of the corresponding pigments were identified through Fourier transform spectroscopy (FTIR) technique thus indicating the presence of cyanidin 3-glycosides and piperine in the flowers of Alstroemeria and Alpinia purpurata. The extracted dyes were immobilized on TiO₂ on transparent conducting FTO glass, which were used as photoanode. The dye-coated TiO₂ photoanode, pt photocathode and iodide/triiodide redox electrolyte assembled into a cell module was illuminated by a light source intensity 100 mW/cm² to measure the photovoltaic conversion efficiency of DSSCs. The TiO₂ anode and Pt counter electrode surface roughness and morphological studies were evaluated using atomic force microscope (AFM) and field emission scanning electron microscopy (FESEM), respectively. Through the photoelectric characterizations, it was promising to verify that the solar conversion efficiency was calculated with the photovoltaic cell sensitized by Alstroemeria and Alpinia purpurata. This was achieved with a yield (η) of 1.74% and 0.65%, with an open-circuit voltage (V_oc) of 0.39 and 0.53 V, short-circuit current density (J_sc) of 2.04 and 0.49 mA/cm², fill factor (FF) of 0.35 and 0.40, and P_max of 0.280 and 0.100 mW/cm², respectively. The results are promising and demonstrate the importance of the search for new natural dyes to be used in organic solar cells for the development of devices that generate electricity in a sustainable way. Full article

(1) Background: Albinism is characterized by a lack of pigment in eyes, hair, and skin and developmental changes in the eye such as foveal hypoplasia. Patients require optical rehabilitation due to low vision, refractive errors, and photosensitivity. We aimed to assess vision-related quality of life in patients with albinism and to evaluate how this was affected by optical rehabilitation. (2) Methods: Patients with ocular or oculocutaneous albinism were invited for the study. Free-of-charge optical rehabilitation was provided as needed, including filters, glasses for near or distance, contact lenses, magnifiers or binoculars. Vision-related quality of life was assessed prior to and after optical rehabilitation using the visual function questionnaire (VFQ39) and the effect of optical rehabilitation was evaluated after accounting for age, gender, and visual acuity. (3) Results: Seventy-eight patients filled out the VFQ39 at the initial visit. Fifty patients (64.1%) returned the questionnaire 3–6 months after optical rehabilitation. The mean age of included patients was 35.9 years (standard deviation 16.6), and their best corrected distance visual acuity was 56 ETDRS letters (range 3–81). The VFQ39 composite score improved significantly from a median of 62.5 (range 14.2–77.0) to 76.5 (20.6–99.6). Significant improvements were seen for ocular pain, social functioning, mental health, role difficulties, and dependency, whereas self-assessed distance or near visual functions did not change. (4) Conclusions: Optical rehabilitation improved the self-reported vision-related quality of life in Danish patients with albinism on a number of parameters related to leading an independent and worry-free life, whereas visual improvement for distance and near tasks was likely limited by the nature of the disease and by the fact that most patients already had access to some optical aids prior to the study. Full article

Photosensitive glasses for radiation-induced 3D microstructuring, due to their optical transparency and thermal, mechanical, and chemical resistance, enable the use of new strategies for numerous microscale applications, ranging from optics to biomedical systems. In this context, we investigated the plasma etching of photosensitive glasses after their exposure and compared it to the established wet chemical etching method, which offers new degrees of freedom in microstructuring control and microsystem fabrication. A CF₄/H₂ etching gas mixture with a constant volumetric flow of 30 sccm and a variable H₂ concentration from 0% to 40% was utilized for plasma-based etching, while for wet chemical etching, diluted hydrofluoric acid (1% ≤ c_HF ≤ 20%) was used. Therefore, both etching processes are based on a chemical etching attack involving fluorine ions. A key result is the observed reversion of the etch selectivity between the initial glassy and partially crystallized parts that evolve after UV exposure and thermal treatment. The crystallized parts were found to be 27 times more soluble than the unexposed glass parts during wet chemical etching. During the plasma etching process, the glassy components dissolve approximately 2.5 times faster than the partially crystalline components. Unlike wet chemical etching, the surfaces of plasma etched photostructured samples showed cone- and truncated-cone-shaped topographies, which supposedly resulted from self-masking effects during plasma etching, as well as a distinct physical contribution from the plasma etching process. The influences of various water species on the etching behaviors of the homogeneous glass and partially crystallized material are discussed based on FTIR-ATR and in relation to the respective etch rates and SNMS measurements. Full article

A highly erbium- and ytterbium-co-doped photosensitive fiber with a germanophosphosilicate glass core was fabricated by the MCVD method, utilizing an all-gas-phase deposition technique developed “in-house”. Due to doping with germanium oxide (GeO₂), this fiber revealed high-grade photosensitivity (without hydrogen loading) to UV laser radiation at a 193 nm wavelength. The short (28 mm) Fabry–Perot laser cavity was designed by inscribing two fiber Bragg gratings (highly and partially reflective FBGs) directly in the core of the fabricated fiber sample. The stable single-frequency operation regime of the designed laser was observed. The laser emission peak was centered at 1540 nm, with a linewidth of 50 kHz. The slope efficiency of the laser was 10%, and the maximal output power reached a level of 35 mW. Full article

The Erbium “random” laser, based on the artificial Rayleigh fiber, has been comparatively studied in detail under two different pump conditions: 974.5 and 1485 nm pumping wavelengths. The artificial Rayleigh 7-m-long fiber was used as a laser cavity, it was formed by the ultraviolet (UV) inscription of the uniform array of the weakly reflective fiber Bragg grating (FBG) during the fiber drawing process. The UV photosensitivity of the Erbium-doped fiber originated from the specially developed (germanophosphosilicate) core glass composition. The emission spectrum of the fabricated “random” fiber laser had a single narrow peak at the 1548 nm wavelength. It was clearly revealed that the extension of the laser cavity by the separate wavelength-matched 90%-reflective FBG resulted in a significant laser efficiency growth. The highest laser slope efficiency of 33% and the laser output power of 80 mW were reached in the FBG-modified cavity at the 974.5-nm-wavelength pumping. The continuous-wave operation mode of this laser has been confirmed. The laser linewidth value measured by the delayed self-heterodyne technique was about 550 Hz. Full article

A new generation of nanoscale photosensitizer agents has improved photothermal capabilities, which has increased the impact of photothermal treatments (PTTs) in cancer therapy. Gold nanostars (GNS) are promising for more efficient and less invasive PTTs than gold nanoparticles. However, the combination of GNS and visible pulsed lasers remains unexplored. This article reports the use of a 532 nm nanosecond pulse laser and polyvinylpyrrolidone (PVP)-capped GNS to kill cancer cells with location-specific exposure. Biocompatible GNS were synthesized via a simple method and were characterized under FESEM, UV–visible spectroscopy, XRD analysis, and particle size analysis. GNS were incubated over a layer of cancer cells that were grown in a glass Petri dish. A nanosecond pulsed laser was irradiated on the cell layer, and cell death was verified via propidium iodide (PI) staining. We assessed the effectiveness of single-pulse spot irradiation and multiple-pulse laser scanning irradiation in inducing cell death. Since the site of cell killing can be accurately chosen with a nanosecond pulse laser, this technique will help minimize damage to the cells around the target cells. Full article

The photosensitive resins for 3D printing technology have been widely applied throughout the advanced communication field due to their merits of high molding accuracy and fast processing speed. Regardless, they, in particular, should have better mechanical properties, heat resistance, and dielectric properties. Herein, photocurable fluorinated poly (phthalazinone ether) (FSt-FPPE) was utilized as a prepolymer to improve the performance of photosensitive resin. A series of UV-curable inks named FST/DPGs were prepared with FSt-FPPE and acrylic diluents of different mass fractions. The FST/DPGs were cured into films by UV curing and post-treatment. After curing, their properties were characterized in detail. In terms of heat resistance, glass transition temperature (T_g) could reach 233 °C and the 5% thermal decomposition temperature (T_d5%) was 371 °C. The tensile strength surprisingly reached 61.5 MPa, and the dielectric constant (D_k) could be significantly reduced to 2.75. Additionally, FST/DPGs were successfully employed in UV-assisted direct writing (DIW) to print 3D objects that benefited from their commendable fluidity and rapid curing speed. A stiff cylinder sample with a smooth surface and distinct pattern was ultimately obtained, indicating their remarkable 3D printing adaptation. Such photosensitive resin for UV-assisted DIW exhibits tremendous potential in the electronic industry. Full article

A charge detector is a vital component in neutrino and dark matter detection. The integration of a charge collector in the form of flat pads and readout modules has been proposed as an optimization method as it can reduce noise and installation complexity. As a substrate, fused silica glass has attracted considerable attention due to its low radioactive background properties. In this research, based on the application requirements of a high charge collection rate and low noise, the structure of the charge detector was designed using calculation and simulation methods. The entire manufacturing process is described. In addition, a novel through glass via (TGV) structure composed of a conformal metal layer and a photosensitive material that is easy to fabricate and has high morphological compatibility with via filling is proposed. The curing property of the new material was characterized. A fully integrated solid-state charge detector with 32 groups of TGVs was realized. Additionally, the electrical properties of key structures were tested and analyzed. Full article

Low-temperature curable negative-tone photosensitive polyimide (n-LTPI) viscous solutions were prepared by dissolving photo-crosslinkable poly (amic ester) (pc-PAE) resin, photophotocrosslinker, photoinitiator, and the heteroaromatic base as curing catalysts, and other additives in organic solvents. Among them, the pc-PAE resin was synthesized by polycondensation of aromatic diacid chloride and diester of 2-ethoxymathacrylate, aromatic diamines in aprotic solvents. After being spun-coated on a silicon wafer surface, soft-baked, exposed to UV light, and developed, the n-LTPI with 2% of imidazole (IMZ) as a curing catalyst produced high-quality photo-patterns with line via resolution of 5 μm at 5 μm film thickness. The photo-patterned polymer films thermally cured at 230 °C/2 h in nitrogen showed 100% of the imidization degree (ID) determined by in situ FT-IR spectroscopy. The thermally cured polymer films exhibited great combined mechanical and thermal properties, including mechanical properties with tensile strength of as high as 189.0 MPa, tensile modulus of 3.7 GP, and elongation at breakage of 59.2%, as well as glass transition temperature of 282.0 °C, showing great potential in advanced microelectronic packaging applications. Full article