Bulletin of the Russian Academy of Sciences: Physics最新文献

Owing to transparency in the near and middle infrared ranges, nanostructures based on arsenic sulfide (As₂S₃) are of interest for designing integrated optics elements. We investigated laser-induced structural and photoluminescence (PL) changes in thermally evaporated and spin-coated vitreous As₂S₃ films. Pulsed (λ = 515 nm, τ = 300 fs) and continuous (λ = 532 nm) laser irradiation was used as a method allowing structural modification without changing the chemical composition of As₂S₃ films. The results of our study reveal laser-induced formation of sulfur S₈ rings and polymer sulfur chains in the spin-coated films, while the local chemical composition of thermally evaporated films does not change. Laser-induced increase in the PL intensity in the range of 1.6–2.0 eV is observed, which is associated with the creation of defect states near the Urbach edge. Laser irradiation presumably increases the amount of homopolar bonds acting as radiative carrier recombination defects, while paramagnetic defects in a form of S dangling bonds do not contribute to PL.

A device for aperture correction at the input of a photovoltaic converter (PPC) module for a power-over-fiber (PoF) system is designed in the form of a lens integrated with an optical fiber, which delivers laser radiation to the input of the PPC crystal. This component allows the beam divergence angle to be significantly increased, with the optimal value being obtained at the input of the PPC module. The lens optical fiber is used to reduce the length of the optical homogenizer, which consequently results in a reduction in the attenuation and mass-dimensional parameters of the entire PPC module. In this configuration, the radiation profile is aligned with the shape and dimensions of the converter crystal, ensuring uniform illumination of the crystal surface. The primary characteristics that impact the efficiency of the operation of the aperture correction device were investigated, including the aperture numerical value, focal length, radiation pattern, and light spot profile. The estimation of optimal parameters for the device used in the photovoltaic conversion module was carried out. The dependence diagrams of the aperture, focal length, and radiation profile on the radius of curvature of the microlens are given.

We report on the fabrication and characterization of localized, Mie-resonant MAPbBr₃ perovskite nanoparticles for efficient light detection. These nanoparticles, exhibiting strong optical resonances in the visible spectrum, were deposited by laser ablation directly onto gold interdigitated electrodes. This method enabled the creation of spatially defined, ultracompact light-sensing elements, with the potential for high integration densities. We demonstrate efficient light detection at 405 nm wavelength using these nanoparticles. Furthermore, we showcase the feasibility of using a pick-and-place technique to precisely position a single nanoparticle between adjacent electrodes. This approach paves the way for the development of ultracompact, nanoscale pixels for high-resolution of low-power light detection applications.

In this manuscript, we present a study on the optical properties of ZnO NWs and microcrystals synthesized via hydrothermal method. The NWs were characterized by low-temperature photoluminescence spectroscopy, which revealed resonance modes indicating random lasing behavior mediated by scattering from misoriented nanowires. The spectral position of the resonance modes suggests lasing in the P-band region of exciton–exciton interaction. Our results also indicate a correlation between the surface density of nanostructures and the peak emission intensity. In addition, optically behavior of individual ZnO microprisms integrated in with a thin perovskite active layer were investigated by room-temperature microphotoluminescence spectroscopy. The results indicate that the ZnO microprisms are efficient optical cavities. Overall, our findings demonstrate the potential of hydrothermal synthesis for the fabrication of efficient ZnO-based light-emitting devices.

The characteristics of emission spectra induced by femtosecond laser filaments in air and water aerosol were studied. Spectra were accumulated 100 ns after 0 ns time delay relative to laser pulse. Second positive (2⁺) ({{N}_{2}}left( {C{{{kern 1pt} }^{3}}Pi _{u}^{{}} - B{{{kern 1pt} }^{3}}Pi _{g}^{{}}} right)) and first negative (1^–) (N_{2}^{ + }left( {B{{{kern 1pt} }^{2}}Sigma _{u}^{ + } - X{{{kern 1pt} }^{2}}Sigma _{g}^{ + }} right)) nitrogen systems were observed. Growth of continuum intensity and noise was observed at transition from filamentation in air to that of in water aerosol. Intensity of 1^– system line decreased more strongly in comparison with 2⁺ system lines for filamentation in water aerosol what explained by quenching collisions of emitters by water molecules. Translational and vibrational temperatures were measured, 329 and 3470 K (filamentation in air), 356 and 3546 K (filamentation in water aerosol).

This study presents the successful synthesis of plasmonic silver nanoparticles (Ag NPs) using laser-induced deposition (LID) on both rigid glass and flexible polydimethylsiloxane (PDMS) substrates. The resulting nanostructures are characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis, demonstrating uniform arrays of Ag nanoparticles with high deposition density and particle sizes ranging from 40 to 90 nm. Silver nanoparticles deposited on PDMS exhibit strong adhesion and maintain structural integrity under mechanical deformations, such as bending and stretching, making them ideal for flexible sensor applications. Surface-enhanced Raman spectroscopy (SERS) measurements using Rhodamine 6G (R6G) as a model analyte reveal that silver nanostructures on PDMS produce a signal comparable to those on glass, with a detection limit of 10^–8 g/L for R6G. This study highlights the potential of PDMS as a flexible substrate for SERS-active sensors in biomedical and environmental applications, providing a scalable and efficient approach for detecting analytes, including disease markers and toxic substances.

We developed theoretical models of light diffraction on multiplexed multilayer inhomogeneous holographic diffraction structures formed in a photopolymer material with varying periods is presented and numerical calculation of diffraction characteristics for such structures are performed. The results received can serve as a basis for further development of spectral filters.

The application of gold nanoparticles for the purpose of seawater desalination is investigated. The efficiency of gold nanoparticles under the action of solar radiation from the water surface, from the bottom and from the water volume is shown. The best efficiency of evaporation of distilled water was obtained for gold nanoparticles from the surface, the evaporation rate is 4.72 kg/(m² h). For comparison, experiments with nanoparticles of MAX phase Ti₂AlC were carried out. The efficiency and prospectivity of using MAX phase Ti₂AlC nanoparticles for water desalination is shown in comparison with other materials. The highest evaporation rate of distilled water for Ti₂AlC nanoparticles was obtained from the water surface it’s equal 4.75 kg/(m² h).

We discussed the possibility of using SPUN fiber in fiber-optic magnetometers. Such a fiber has a property to preserve the circular polarization of radiation passing through it. When SPUN fiber is affected by external factors, the length of polarization beats changes. It is shown that external mechanical effects and the applied magnetic field make the main contribution to the change in the length of polarization beats of SPUN fiber. In this paper a layout scheme is presented, which allows to register an external magnetic field of the order of 0.01 T.

Laser irradiation of As₅₀Se₅₀ thin films leads to fabrication of laser-induced periodic surface structures in them. The mutual influence of the energy and/or number of laser pulses on the evolution of the formed surface structures was shown. Birefringence and optical transmission of the inscribed in different regimes structures were measured. A possibility of using LIPSS for creating optical elements with a phase retardance of up to 50 nm per one layer, as well as a possibility of their multilayer recording were shown.