Interaction Of Laser Radiation Research Articles

Second harmonic generation in structures with inhomogeneous magnetization distribution

The study of the interaction of laser radiation with ferromagnetic materials is not only an inexhaustible source of new effects, but also provides an opportunity to study magnetic media at the micro- and macroscale. This is especially important for the development of modern technologies to produce structures with fundamentally new magnetic and optical properties that can’t be observed in natural materials. The review presents the results of studies of nonlinear optical effects in ferromagnetic nano- and microstructures, as well as films of different compositions. The unique capabilities of nonlinear-optical diagnostics of anisotropic, vortex, exchange-biased magnetic structures, visualization of the micromagnetic structure of the surface layers of ferrite garnets, based both on the high sensitivity of the optical second harmonic generation method to the magnetic state of nanostructures and interfaces, and on the symmetry properties of high-order magnetizationinduced susceptibility tensor have been demonstrated.

Advanced Laser Nanofabrication Technologies for Perovskite Photonics

AbstractHalide perovskites have become a versatile platform not only for optoelectronic devices but also for modern optics and nanophotonics. Perovskite nano‐ and micro‐particles, metasurfaces, and photonic crystals demonstrate their applicability for directional enhanced photo‐ and electro‐luminescence, lasing, as well as for improving the performance of optoelectronic devices. However, ionic nature makes perovskites water soluble, while their high sensitivity to diverse chemicals complicates their patterning toward the formation of functional, high‐quality nanostructures. Here, recent progress on emerging laser technologies for processing and nanopatterning of halide perovskites, as well as their applications in designing advanced light‐emitting systems and controlling light at the nanoscale is overviewed. Special emphasis is made on the processes underlying the interaction of laser radiation with perovskites to disclose new avenues for their surface and volume modification with ultra‐high precision and a high degree of material's property control.

Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N2+

Quantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter, regardless of how many optical frequencies are involved. Here, we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser pulses. In the spectral domain, Fano resonance is observed in the emission spectrum, where a laser-assisted dynamic Stark effect creates the continuum. In the time domain, the fast-evolving emission is measured, revealing the nature of free-induction decay arising from quantum radiation and molecular cooperativity. These findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be universal. The present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance.

Modeling laser processing of materials

For a long time, the complexity of the phenomena occurring during the laser exposure to the material made possible the mainly experimental selection of processing modes. The analysis of the thermal processes taking place at the same time and the programs being used require in-depth knowledge of physical phenomena, as well as broad capabilities of computing equipment, so they have become inaccessible to many researchers. Goal. The purpose of the study is to model the interaction of laser radiation with substance on the example of acrylic glass using the COMSOL Multiphysics 5.5 software package. Methodology. The scrap material for research was acrylic extrusion glass according to GOST 17622-72 and GOST 10667-99. Successful laser treatment requires maximum absorption of radiation, so a CO2 laser with a wavelength of 10.6 microns was chosen for the research. Other laser processing parameters (power 10 W, focus point diameter 1 mm, pro-menu movement speed 40 mm/s) are typical for the StoLaser Standard 4030 Mini installation. Results. The main task was modelling of the interaction of laser radiation with substance on the example of acrylic glass using the COMSOL Multiphysics 5.5 software package. The paper investigates the peculiarities and nature of the interaction of laser radiation with acrylic glass using the finite element method, as well as with the help of the COMSOL software complex, which works according to this method. A program for modelling the interaction of a laser beam with a material, in this case non-metallic, was created experimentally. A graphical distribution of heat on the surface and an isotherm of the depth of heat distribution inside the material were obtained. Scientific novelty. In this paper, a model of the passage of laser radiation through a block of dielectric material was created using the COMSOL Multiphysics package. The possibility of modeling laser processing of materials by the finite element method was proven. Practicality. The developed model can be used when choosing the modes of laser processing of various materials.

GaSe nanoparticles synthesized by laser ablation method

GaSe nanoparticles obtained by direct interaction of laser radiation with Ga element and SeO2 solution were experimentally investigated. A pulsed Nd:YAG laser with a duration of 10 ns and an energy of 135 mJ per pulse was used as the radiation source. The formation of nanoparticles with diameters ranging from 2 to 25 nm was observed in the colloidal solution. By X-ray diffraction analysis it was found that the crystal structure of the nanoparticles is the same as that of the bulk material (hexagonal). It is shown that the photoluminescence emission of the obtained nanoparticles has a dark orange color and is associated with the radiative recombination of free excitons.

Picosecond Laser-Induced Bump Formation on Coated Glass for Smart Window Manufacturing

We report a study on the process of the formation of bubble-like structures on a coated glass surface using 50 ps laser pulses. The high-intensity interaction of laser radiation on the film–glass interface allowed us to develop a process for efficient glass bump formation. The high peak energy of the picosecond pulses has allowed us to merge the processes of coating evaporation and bubble growth into one. A parameter window was established within which efficient bump formation can be achieved. Well-defined spherical structures with a height up to 60 μm and a diameter up to 250 μm were obtained at pulse energy Epulse = 2.5 ÷ 4 μJ and laser fluence F = 2.5–0.41 J/cm2). The key aspects of the bump formation process were studied and are explained.

ВИБІР ТЕХНОЛОГІЧНИХ ПАРАМЕТРІВ ЛАЗЕРА ДЛЯ ОТРИМАННЯ НАНОСТРУКТУР НА ІНСТРУМЕНТАЛЬНІЙ СТАЛІ У12А

According to the improved model of the thermal interaction of laser radiation and the processing material, a study of the change in the maximum temperature at different depths of the surface layer was carried out on the example of tool steel U12A. The rate of change of the maximum temperature and temperature stress as a function of the heat flux density of laser radiation (LV) was also studied. The range of LV density was taken within q=108...1011 W/m2 for different times of its action, which corresponds to the conditions for the possible occurrence of NS. The study of the dependence of the rate of change of the maximum temperature on U12A steel on the density of the heat flow at different depths showed that during all times of its action, rates of temperature change of more than 107 K/s are realized, which indicates that, according to this criterion, the formation of NS is possible over the entire range of densities heat flow and at all investigated depths. To determine the possibility of accelerating the formation of NS, the values of temperature stresses in the zone of action on U12A were calculated at a density of 108...1011 W/m2 at different depths with an action time of t=10-4 ...10-10c. Which showed that the direct formation of NS from the action of temperature stresses is practically impossible, however, at a time of 10-5...10-4 of their values, they approach those required at a heat flux density of 1011 W/m2. In order to determine the technological parameters that ensure the production of NS, spatial dependences of the volume of NS on the heat flux density and the time of its action were constructed for the radius of the spot R=10-6 m (Fig. 8) and R=5•107 m (Fig. 9) . It was determined that obtaining NS is more realistic for the size of the spot 5•107 m, although the probability of obtaining them is also low. In fig. 10 and 11 show similar dependences for the grain size on the heat flux density and the time of its action for the spot size R=10-6 m and R=5•107 m when acting on U12A tool steel. The obtained spatial pictures allow, knowing the required grain size, to choose the technological parameters that allow them to be implemented. All this will be required during the development of the technology for obtaining strengthening nanostructured coatings on the cutting tool.

Possibility of Observing Radiation Effects in the Interaction of Ultrahigh-Power Laser Radiation of a Magnetic Dipole Configuration with Plasma

Possibility of Observing Radiation Effects in the Interaction of Ultrahigh-Power Laser Radiation of a Magnetic Dipole Configuration with Plasma

Optical Properties of Nanoparticles Dispersed in Ambient Medium and their Dependences on Temperature

Abstract: This review describes the basic and application aspects of the optical properties of nanoparticles (NPs), which determine the dynamics and results of optical (laser) radiation interaction with NPs and their surroundings through NP light absorption and heat generation. In addition to the importance of primary optical processes, the thermal application of the light–NP interaction has attracted significant interest from various areas ranging from photochemistry to laser material processing and nanobiomedicine. First of all, the information provided is intended for laser specialists, photochemists and nanobiologists who are not so familiar with various optical data for understanding of the influence of NP optical properties on the results of optical or laser action on NPs and medium. Secondly, our review will be useful for researchers who conduct high-temperature investigations of the intense optical action on NPs that needs to take into account the dependence of NP optical properties on its temperature under NP heating. Our attention is focused on two variants of the applications of NP optical properties. Firstly, we shortly reviewed the optical properties of NPs at their initial or slightly higher temperatures reached under the influence of moderate radiation intensity. They are presented in numerous publications and are used as basic data. On the other side, the development of modern high-temperature laser and optical technologies needs to use the NPs optical properties at temperatures of about 1x103 K and more. For high power laser and optical technologies, it is necessary to take into account the temperature dependences of the optical parameters of various metals, dielectrics and other materials. Among these technologies, one should list laser processing of NPs, thermal laser biomedicine, solar and photo nanocatalysis, solar nanostructured absorbers. The selection and use of suitable optical properties of NPs are crucial to successful achievements and results in high-temperature experiments and applications. Novel information on optical property dependence on temperature obtained from currently available literature has been presented for possible applications in optical and laser high-temperature processes interactions with NPs. However, unfortunately, the essential information on the effect of temperature on the optical properties of NPs is currently limited. In addition to the latest information, this review also includes the figures obtained by our own calculations to provide readers with a better understanding of the NP optical properties. From the side of the application, the use of NP optical properties is considered, which provide multiple varieties of moderate and high-temperature technology opportunities, many of which are ongoing and some of them are promising bright results in the near future. The beneficial outcome and the results of further activities in the research of intense laser and optical interactions with NPs can influence various fields of science and technology: nano and photochemistry, biomedicine, nanophysics, material science, etc.

The Role of Stepwise Photoionization in Measurements of the Ionization Potentials in Dense Plasma

The interaction of high-contrast high-intensity laser radiation with solids allows us to create hot or warm plasma of solid or even over-solid density, such as in the case of inertial fusion particularly. The multicharged ions contained in it can no longer be considered isolated. As a result, this leads to a decrease in the ionization potentials and to the disappearance of a number of bound ionic states. To describe the ionization potential depression, two major approaches are now used predominantly, where the key parameter is either average interelectronic or interionic distance. Since neither of the approaches can be substantiated purely theoretically, their applicability can only be established by comparison with experimental results. In recent experiments with X-ray free-electron lasers, it was concluded that the ionization potential depression rather depends on the interelectronic distance. However, when measuring ionization potentials, it was assumed that the main role in ionization processes is played by the direct photoionization of the ion ground state. In the present paper, we show that stepwise photoionization processes should play a significant role in dense plasma, disrupting a straight correspondence between the threshold in direct photoionization by X-ray laser photons and the actual ionization potential of multicharged ions. It means that the measurement results mentioned above are not correct, and the main conclusion about the importance of the interelectronic distance for depression of the ionization potential is not correct.

Coherent Population Trapping Resonance Parameters and Field Shifts during the Detection of Signals from Different Cross-Sectional Areas of the Interaction of Laser Radiation with Atoms

Coherent Population Trapping Resonance Parameters and Field Shifts during the Detection of Signals from Different Cross-Sectional Areas of the Interaction of Laser Radiation with Atoms

On Possible Mechanism of Enhancement of Absorption of Powerful Laser Radiation by Metals

In this work, it is shown that the dependence of the mass of conductive band electrons in a metal on their energy can be a reason of enhancement of the absorption of powerful laser radiation by the metal. To do this, a problem of response (current) of the electron placed in one-dimension periodic potential (lattice) to an electric field periodic in time (electromagnetic wave) is solved. The solution shows that for sufficiently large amplitude of the wave the dependence of the electron current on the wave amplitude becomes non-linear. Within a certain rangе of parameters, this dependence can be described by a simple formula that corresponds to the dependence of the electron mass on its energy. The formula was used for solving the problem of penetration of electromagnetic wave into a metal with the approach of modified Drude model. The non-linearity results in the enhancement of the wave absorption and generation of wave with frequencies close to those of plasma penetrating deep into the metal. The discussed effects manifest themselves in electric fields about. 1 V/Angstrom. The obtained results can be used in the interpretation of experiments data and in the creation of mathematical modeling of the interaction of powerful laser radiation with metal.

XXII International Conference and School on Quantum Electronics: “Laser Physics and Applications”

The International School on Quantum Electronics “Laser Physics and Applications” was held for the first time as far back as 1980. Since then it has taken place biennially and has become an important international event in the field of laser physics and laser applications attracting participants from many countries, especially from south-eastern Europe. Traditionally, its program includes lectures delivered by prominent scientists dealing with investigations of basic physical phenomena, processes of interaction of laser radiation with matter and latest scientific results obtained in the research areas of quantum electronics and optics, as well as the technological practical applications of new ideas, devices, instruments and laser systems. Special attention is paid to the active participation of students and young scientists who have the opportunity to present their results and meet and share experience with outstanding professionals in their particular fields of research.The topics include the following:• Laser-matter interactions • Laser spectroscopy and metrology • Laser remote sensing and ecology • Lasers in biology and medicine • Laser systems and nonlinear optics • Alternative techniques for material synthesis and processing The 22nd edition of the ICSQE was held as a virtual forum due to the restrictions related to COVID-19 pandemic from September 19th to 23rd, 2022. The Institute of Electronics, Bulgarian Academy of Sciences, located in Sofia, Bulgaria, hosted the conference organization. The Big Blue Button on-line system was used as a technical platform for the meeting. The technical sessions of the International School on Quantum Electronics included 22 invited talks (30 min + 5 min Q&A), a Mini-Symposium “Extreme light infrastructure”, 11 oral contributions (30 min + 5 min Q&A) and in total 51 poster presentations divided into 5 sessions (1 hour each). The platform was available 24 hours, allowing discussions in addition to the technical program. The total number of participants was 90 from 16 countries.The XXII International Conference and School on Quantum Electronics: “Laser Physics and Applications” was held by the financial support from the Bulgarian National Science Fund under Project No. KP-06-MNF/4, 20.07.2022.List of Committees, International Advisory Committee, Program Committee, Local Organizing Committee, Lecturers, Oral Presentations, Poster Presentations are available in this pdf.

Efficient Generation of Attopulses at the Interaction of Intense Laser Radiation with Ultrathin Targets

Efficient Generation of Attopulses at the Interaction of Intense Laser Radiation with Ultrathin Targets

Resonance Interaction of High-Power Laser Radiation with Plasma in a Strong Magnetic Field (a Review)

Resonance Interaction of High-Power Laser Radiation with Plasma in a Strong Magnetic Field (a Review)

Influence of collisions on the effect of electromagnetic-induced transparency in cells of finite sizes with anti-relaxation coating of walls

Based on the semiclassical theory of the interaction of two-frequency laser radiation with a resonant atomic medium, an analytical expression is obtained that describes the form of resonances of electromagnetically induced transparency detected in a cell with a finite direction in the longitudinal laser beam direction with an anti-relaxation coating of walls, taking into account the motion of atoms and collisions with walls. The following types of reflection from walls are considered: diffuse, specular, and specular-incoherent. It is found that in a number of cases the diffuse type of reflection exhibits the properties of a mirror-incoherent one. It is also shown that the nondegeneracy of the excited state in a number of cases significantly changes the shape of the transparency resonance. Keywords: Electromagnetically induced transparency, Gas cell, anti-relaxation coating, diffuse reflection, specular reflection, specular-incoherent reflection.

Влияние столкновений на характер эффекта электромагнитно-индуцированной прозрачности в ячейках конечных размером с антирелаксационным покрытием стенок

Based on the semiclassical theory of the interaction of two-frequency laser radiation with a resonant atomic medium, an analytical expression is obtained that describes the form of resonances of electromagnetically induced transparency detected in a cell with a finite direction in the longitudinal laser beam direction with an anti-relaxation coating of walls, taking into account the motion of atoms and collisions with walls. The following types of reflection from walls are considered: diffuse, specular, and specular-incoherent. It is found that in a number of cases the diffuse type of reflection exhibits the properties of a mirror-incoherent one. It is also shown that the nondegeneracy of the excited state in a number of cases significantly changes the shape of the transparency resonance.

The Investigation of the effect of laser radiation on the dielectric properties of polymethylmethacrylate

The problem of studying the interaction of laser radiation with polymer materials lies in the study of the effect of intense energy fluxes on matter. The effect of pulsed laser radiation on a high-molecular substance was studied from changes in the electrical parameters of the irradiated materials. Changes in ε’, tg δ depending on the frequency of the external field, the dose of laser irradiation, temperature and time were investigated by a highly sensitive physicochemical method -the method of dielectric losses. This article examined the impact of laser radiation on the dielectric properties of polymethylmethacrylate at frequency of 50 kHz within the temperature interval from 170 to 420 K. The authors showed that the processing of the samples with laser radiation leads to substantial changes in the dielectric constant and tangent of dielectric loss angle.

Influence of the focusing characteristics of near-infrared lasers on the maintenance of plasma luminescence

The interaction of 980-nm continuous laser radiation with the plasma of a continuous optical discharge in xenon lamps at a pressure of p = 12 atm has been studied. The threshold power and characteristics of the laser required to sustain the xenon plasma became our focus. According to the theory of Gaussian beam propagation, the laser parameters after collimation and focusing are obtained by combining ZEMAX simulation and the actual measurement. The influence of the beam waist ω0, which determines the power density distribution at focus, and the Rayleigh range Z0, which determines the energy concentration range, on the threshold maintenance power is expounded. The results show that there is a threshold power density for the generation of plasma, whose value is about 1,500–2,000 W/mm2, and that the threshold maintenance power of the plasma shows an overall decreasing trend with decreasing ω0. When ω0 is reduced to a higher power density that can easily maintain the thermodynamic equilibrium process of the plasma, the mismatch between Z0 and the plasma size caused by the decrease in Z0 makes the threshold power tend to be stable and increasing.

FEATURES OF THE DYNAMICS OF EROSION PLUMES AT THE ACTING OF INTENSIVE NANOSECOND LASER PULSES ON A GRAPHITE TARGET IN VACUUM

The temporal characteristics of the glow intensity of erosion laser plumes near the surface under the action of nanosecond laser pulses on a carbon target are experimentally studied. The interaction of laser radiation with the destruction products of plume is minimal due to the formation of erosion plasma with a delay relative to the acting laser pulse. Using a modernized spectrometer, the spectral characteristics of an erosion
 laser plume near the surface of a carbon target with a time resolution of 10–8 s are studied, and the characteristic plasmodynamic times in the plume are ~10–6 s. It is shown that the emission of spectral lines of carbon appears with a delay relative to the glow of the continuous background, when the erosion plume is cooled during expansion. The results of the study make it possible to optimize some characteristics of the laser-
 plasma source for the deposition of nanocoatings.