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In this paper, two parameters of the applied magnetic field—magnetic field strength and pulse length—are modified, the spatial properties of electron trajectories and radiation are studied, and conclusions are drawn. Under the premise that the radius of the laser pulse waist b 0 = 4 λ 0 , and that the peak amplitude a 0 = 5 corresponds to the peak laser intensity I L = 3.45 × 10 19   W / c m 2 of the electrons, obtaining high-energy and highly collimated X-rays can be realized by increasing the pulse length up to 6 λ 0 and increasing the magnitude of the applied magnetic field, or by continuously increasing the pulse length and applying a smaller magnetic field. [ABSTRACT FROM AUTHOR]

Based on the classical theory of nonlinear Thomson scattering and the single electron model, we performed extensive numerical simulations in MATLAB R2022b to comprehensively investigate how the initial phase of a tightly focused, circularly polarized laser pulse affects the radiation characteristics of high-energy electrons at different energy levels. Our findings indicate that the polar angle corresponding to the maximum radiation energy remains constant as the initial phase of the laser changes from 0 to 2π, while the azimuth angle correspondingly moves from 0 to 2π. Moreover, as the initial phase changes, the pulse width of the electron radiation peak displays a quasi-periodic oscillation with a period of π. Notably, an increase in the initial energy of the electrons results in a significant enhancement in both the peak radiation value and the collimation of the radiation. These results demonstrate that manipulating the initial phase of the driving laser pulse enables effective control over the spatial distribution of radiation light. [ABSTRACT FROM AUTHOR]

A universal technique is developed for the detection of high harmonics generated by relativistic and subrelativistic laser pulses irradiating a solid target. Features in the spectra of harmonics generated by a parametric mid-IR laser system and near-IR laser system based on chirped pulse amplification were analyzed. Experimental spectra of harmonics in the range up to 35 nm were recorded. They can be used as a source of coherent radiation in the extreme UV region. [ABSTRACT FROM AUTHOR]

Background and Objectives: A brief biography of Valery Tuchin, head of Optics and Biophotonics Department of Saratov State University, Doctor of Physical and Mathematical Sciences, Professor, Corresponding Member of the Russian Academy of Sciences is presented; his contribution to laser physics and biophotonics is discussed. Summary: Scientific activity of Valery Tuchin in the 60s was associated with laser physics. His interests included fluctuations in laser radiation, dynamic processes in gas-discharge lasers, and modulation characteristics of lasers. In the mid-80s, Professor Valery Tuchin began to create his own scientific school in the field of tissue optics, which eventually developed into the interdisciplinary science of biomedical photonics, and pioneered “tissue optical clearing” as a new direction. Over the years, the results achieved have received international recognition. Tuchin’s students continue to move along a given vector, developing his ideas and achieving great success and recognition not only in Russia but also abroad. He generously shares ideas with colleagues, connecting Saratov State University with scientific groups around the world. His authority and charisma, as well as his tremendous energy and efficiency, make it possible to implement great international projects, conferences and symposiums. Valery Tuchin is the organizer and inspirer of the Saratov Fall Meeting, which is widely known in the scientific world. Thanks to Valery Tuchin, students and young scientists from Saratov State University were among the first in Russia to have the opportunity to listen to lectures of heads of leading scientific groups, present and discuss their results, establish scientific and friendly connections with peers from other cities of the world. From 1989 to the present, Valery Tuchin has been the permanent head of the Optics and Biophotonics Department at Saratov State University. Conclusion: Professor Valery Tuchin is a unique example of both an outstanding scientist and a talented teacher and organizer of the scientific process. He have created a scientific school known all over the world. His fruitful scientific and educational activities have marked by the awarding of medals, orders, honorary titles and prizes from the State and various scientific communities, as SPIE, OCA, Laser Association of the Russian Federation and others.

Based on Thomson scattering classical theory and single electron model, numerical simulation of Thomson scattering X-ray source is completed with the help of MATLAB software. We discuss the influence of waist radius and initial phase of few-cycle laser pulse on maximum radiation energy, maximum radiation power, radiation angle distribution and spectrum when the collision center is at or away from the focus. It is found that the initial z-axis position of the electron has no effect on the overall change trend. The influence ability of waist radius appears a "watershed" phenomenon at b 0 = 4 λ 0 . When b 0 = 1 ∼ 3 λ 0 , with the increase in the waist radius, the maximum radiation energy and the maximum radiation power increase, and the collimation of laser and the monochromaticity of the spectrum become worse. When b 0 ≥ 4 λ 0 , the change in waist radius has no effect on these parameters. In addition, when the initial phase of few-cycle laser pulse increases in the range of 0–360°, the maximum radiation direction rotates counterclockwise, and the values of the maximum radiation energy and the instantaneous power of the maximum radiation energy and the peak value of the spectrum fluctuate only in a small range. [ABSTRACT FROM AUTHOR]

In this paper, two parameters of the applied magnetic field—magnetic field strength and pulse length—are modified, the spatial properties of electron trajectories and radiation are studied, and conclusions are drawn. Under the premise that the radius of the laser pulse waist b0=4λ0, and that the peak amplitude a0=5 corresponds to the peak laser intensity IL=3.45×1019 W/cm2 of the electrons, obtaining high-energy and highly collimated X-rays can be realized by increasing the pulse length up to 6λ0 and increasing the magnitude of the applied magnetic field, or by continuously increasing the pulse length and applying a smaller magnetic field.

The effects of magnetic fields on electron dynamics, spatially radiated power, and radiation spectra in tightly focused circularly polarized laser pulses are studied in detail. The laser wavelength λ 0 = 1   μ m . As the pulse width increases from λ 0 to 6 λ 0 , the electron dynamics, spatially radiated power, and spectral properties stabilize, and the benefit that can be enhanced by increasing the pulse width decreases continuously, i.e., saturation is reached. However, although the benefits are better at pulse widths equal to 6 λ 0 , to obtain high-energy, highly collimated X-rays, tightly focused circularly polarized laser pulses with larger pulse widths is better. [ABSTRACT FROM AUTHOR]

Based on Thomson scattering classical theory and single-electron model, we study the spatial spectrum and spectrum of laser driven high-energy electron radiation corresponding to different waist radius and initial phase. With the help of MATLAB software to complete the numerical simulation, we find that with the initial phase is unchanged, when the beam waist radius b 0 increases, the trajectory of the electron does not change significantly. The main peak of the three-dimensional spectrum will rise slightly near b 0 = 2.2 λ 0 , and then decline sharply, and the corresponding harmonic number is also declining. While the secondary peak keeps rising, and its corresponding harmonic frequency also keeps rising. When the initial phase value is larger, the sharp drop of the main peak and the sharp rise of the secondary peak in the spectrum will be more obvious, and the secondary peak is more sensitive to the change of polar angle. In the spatial spectrum, the angle range will increase with the increase in b 0 , and the collimation will become worse. In addition, when the beam waist radius is unchanged and the electron collides at the focus, the monochromaticity of the scattering spectrum and the highest harmonic number of energy are not affected by the initial phase, and the change of the initial phase makes the maximum single harmonic energy of the scattered light change periodically, with its period of π , and the curve is approximate to a trigonometric function curve. When the initial phase increases, it can be seen from the top of the spatial spectrum that the maximum radiation direction rotates counterclockwise. When the pulse width increases, the monochromaticity of the spectrum becomes worse, the width becomes narrower, and a redshift phenomenon occurs. These results will be helpful to understand the nonlinear Thomson scattering. [ABSTRACT FROM AUTHOR]

Based on the classical theory of nonlinear Thomson scattering and the single electron model, we performed extensive numerical simulations in MATLAB R2022b to comprehensively investigate how the initial phase of a tightly focused, circularly polarized laser pulse affects the radiation characteristics of high-energy electrons at different energy levels. Our findings indicate that the polar angle corresponding to the maximum radiation energy remains constant as the initial phase of the laser changes from 0 to 2π, while the azimuth angle correspondingly moves from 0 to 2π. Moreover, as the initial phase changes, the pulse width of the electron radiation peak displays a quasi-periodic oscillation with a period of π. Notably, an increase in the initial energy of the electrons results in a significant enhancement in both the peak radiation value and the collimation of the radiation. These results demonstrate that manipulating the initial phase of the driving laser pulse enables effective control over the spatial distribution of radiation light.

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Upcoming and planned experiments combining increasingly intense lasers and energetic particle beams will access new regimes of nonlinear, relativistic, quantum effects. This improved experimental capability has driven substantial progress in QED in intense background fields. We review here the advances made during the last decade, with a focus on theory and phenomenology. As ever higher intensities are reached, it becomes necessary to consider processes at higher orders in both the number of scattered particles and the number of loops, and to account for non-perturbative physics (e.g. the Schwinger effect), with extreme intensities requiring resummation of the loop expansion. In addition to increased intensity, experiments will reach higher accuracy, and these improvements are being matched by developments in theory such as in approximation frameworks, the description of finite-size effects, and the range of physical phenomena analysed. Topics on which there has been substantial progress include: radiation reaction, spin and polarisation, nonlinear quantum vacuum effects and connections to other fields including physics beyond the Standard Model. [ABSTRACT FROM AUTHOR]

2023 is the year of commemoration of M.L. Ter-Mikayelian, a scientist who had important contribution to high energy physics, coherent bremsstrahlung, quantum and nonlinear optics, quantum electronics and laser physics, high-temperature superconductivity, and related fields. This article is scientific biography of the outstanding scientist. The range of scientific interests of M.L. Ter-Mikaelyan was really wide. In this issue, we tried to collect the works of his students and followers. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of magnetic fields on electron dynamics, spatially radiated power, and radiation spectra in tightly focused circularly polarized laser pulses are studied in detail. The laser wavelength λ0=1 μm. As the pulse width increases from λ0 to 6λ0, the electron dynamics, spatially radiated power, and spectral properties stabilize, and the benefit that can be enhanced by increasing the pulse width decreases continuously, i.e., saturation is reached. However, although the benefits are better at pulse widths equal to 6λ0, to obtain high-energy, highly collimated X-rays, tightly focused circularly polarized laser pulses with larger pulse widths is better.

Quantum cascade lasers (QCLs) have broken the spectral barriers of semiconductor lasers and enabled a range of applications in the mid-infrared (MIR) and terahertz (THz) regimes. However, until recently, generating ultrashort and intense pulses from QCLs has been difficult. This would be useful to study ultrafast processes in MIR and THz using the targeted wavelength-by-design properties of QCLs. Since the first demonstration in 2009, mode-locking of QCLs has undergone considerable development in the past decade, which includes revealing the underlying mechanism of pulse formation, the development of an ultrafast THz detection technique, and the invention of novel pulse compression technology, etc. Here, we review the history and recent progress of ultrafast pulse generation from QCLs in both the THz and MIR regimes. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article is based on the annual reports presented by the Head of the Physical Sciences Division of the Russian Academy of Sciences at the General Meetings of the Division in April 2021 and April 2022. It describes some scientific results in physics obtained in 2020–2021 at the research institutions (institutes of the Russian Academy of Sciences) under the individual powers of the Russian Academy of Sciences stipulated by the regulations of the Government of the Russian Federation no. 521 dated June 5, 2014, and no. 1652 dated December 24, 2018. The information about the research in different fields of physics carried out at these institutions is summarized briefly and illustrated by examples of some bright scientific breakthroughs. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present an optical setup for well-defined ionization inside a plasma such that precisely controlled spots of high electron density can be generated. We propose to use the setup for Trojan Horse Injection (or Plasma Photocathode Emission) where a collinear laser beam is needed to release electrons inside a plasma wakefield. The reflection-based setup allows a suitable manipulation of the laser near field without disturbing the spectral phase of the laser pulses. A required ionization state and volume can be reached by tuning the beam size, pulse duration and pulse energy. The ionization simulations enable a prediction of the ionization spot and are in good agreement with dedicated experiments which measured the number of electrons created during the laserâ€"gas interaction. [ABSTRACT FROM AUTHOR]

We present a short review of the history of researches in quantum and laser physics at the Lebedev Physical Institute and mention some aspects of international collaboration. [ABSTRACT FROM AUTHOR]

An adaptive learning algorithm coupled with 3D momentum-based feedback is used to identify intense laser pulse shapes that control H3+ formation from ethane. Specifically, we controlled the ratio of D2H+ to D3+ produced from the D3C-CH3 isotopologue of ethane, which selects between trihydrogen cations formed from atoms on one or both sides of ethane. We are able to modify the D2H+:D3+ ratio by a factor of up to three. In addition, two-dimensional scans of linear chirp and third-order dispersion are conducted for a few fourth-order dispersion values while the D2H+ and D3+ production rates are monitored. The optimized pulse is observed to influence the yield, kinetic energy release, and angular distribution of the D2H+ ions while the D3+ ion dynamics remain relatively stable. We subsequently conducted COLTRIMS experiments on C2D6 to complement the velocity map imaging data obtained during the control experiments and measured the branching ratio of two-body double ionization. Two-body D3+ + C2D3+ is the dominant final channel containing D3+ ions, although the three-body D + D3+ + C2D2+ final state is also observed.

In order to know micron focal switch of polychromatic TEM22 mode Hermite-Gaussian (HG) beams passing through an apertured dispersion lens system, numerical calculation examples were used to study the beam's intensity distributions. The data of the axial intensity distributions were achieved. It is found that variation of the bandwidth results in change of two maximal intensities of TEM22 mode (HG) beams and thus position of the principle maximal intensity shifts rapidly. When relative bandwidth γ is 0.231 and Fresnel number Fw is 100, the position varies 2.5 µm and the phenomenon of micron focal switch presents. The bandwidth and Fresnel number are important factors that induce the micron focal switch. A narrow bandwidth is enough to induce the focal switch of TEM22 mode (HG) beams in the system with large Fresnel number whereas a broad bandwidth is required in the system with small Fresnel number. Results in this paper help the design and manufacture of micro and nano optical devices in optical communication technique. [ABSTRACT FROM AUTHOR]

In order to study the spatial correlation properties of tightly focused J0 -correlated radially polarized vortex beam through a high numerical aperture dNA, the vectorial Debye diffraction theory and the coherence theory were adopted. After theoretical analysis and numerical simulation of the correlation characteristics of focused field on the optical axis and the focal plane, the expression and simulation data of coherence degrees were obtained. The results show that,the longitudinal coherence degrees in the focal region increase as the topological charge n increases, but it decrease as the coherence parameter or the numerical aperture dNA; The transverse coherence degrees in the focal plane decrease with the increase of the topological charge, coherence parameter or numerical aperture. When n ≥ 5 or dNA ≤ 0. 4, the longitudinal coherence near the focal point approximately equals to 1. Further, the coherence degrees are shown to exhibit phase singularities. The results are of great significance to the application of J0 -correlated vector vortex beams in many fields. [ABSTRACT FROM AUTHOR]

The extreme ultraviolet (EUV) light conversion efficiency of the laser-produced tin plasma is closely related to the plasma characteristics. To diagnose the parameters of tin plasma, a Langmuir probe for laser-produced plasma diagnosis was designed. And the time evolution of electron temperature and electron density of tin plasma produced by different laser energies were studied. The results show that the peak electron density of the plasma is about 4. 5 x 1011 cm-3 with laser energy of 58.1 mJ, and the maximum electron temperature is 16.5eV, which decreased with the reduction of laser energy. Moreover, the evolution trends of electron temperature measured by Langmuir probe and emission spectrometry are consistent. This study provides a new simple and rapid diagnostic method for laser-produced plasma EUV light source, which is beneficial to optimize the parameters of EUV light. [ABSTRACT FROM AUTHOR]

In this research, amplified spontaneous emission (ASE) is studied along a rod amplifier length where intensities travel in two opposite longitudinal axis directions. The effect of ASE intensity on amplifier stored energy was discussed. An expression was obtained for stored energy in an amplifier in which a nonuniform gain distribution shaped due to ASE saturation effect. Time evolution of population inversion in a pulsed amplifier at the presence of ASE effect was also obtained, using the new relation of stored energy. Numerical calculations were used to verify accuracy and validity of the obtained relations. The numerical calculations included solving rate equation of population inversion of amplifier and simultaneous solving of two intensity equations for two beams traveling in opposite directions along the amplifier length. [ABSTRACT FROM AUTHOR]

In order to study the relationships of the intensity and distribution of electromagnetic pulses (EMP) with laser parameters, target materials and configuration, the ultra-small B-dot antenna inside the target chamber was used to measure the electromagnetic pulses generated during the strong laser shooting metal copper targets. The pulse intensities in different radiation directions were analyzed. At the same time, electromagnetic radiation in the cases where the target support rod was an insulator and a conductor were discussed. The electromagnetic pulse shows a maximum value of 20V in the normal direction and 22V for the conductive rod, which indicates that EMP induced by strong laser targets has a strong polarized direction and can produce stronger electromagnetic radiation in the case of conductive target rods. The conclusion of this experiment is helpful for revealing the transmission polarization characteristics of EMP generated by laser target interaction in the target chamber and the relationship between its intensity and the conductivity of the target rod. [ABSTRACT FROM AUTHOR]

Small-sized vertical-cavity surface-emitting laser (VCSEL) offer the possibility of very low power consumption along with high reliability for cryogenic data transfer. Cryogenic data transfer has applications in focal plane array cameras operating at 77 K, and at the lower temperature of 4 K for data extraction from superconducting circuits. A theoretical analysis is presented for 77 K and 4 K operation based on small cavity, oxide-free VCSEL sizes of 2 to $6~\mu \text{m}$ , that have been shown to operate efficiently at room temperature. Temperature dependent operation for optimally-designed VCSELs are studied by calculating the response of the laser at 77 K and 4 K to estimate their bias conditions needed to reach modulation speed for cryogenic optical links. The temperature influence is to decrease threshold for reducing temperature, and to increase differential gain for reducing temperature. The two effects predict very low bias currents for small cavity VCSELs to reach needed data speed for cryogenic optical data links. Changing the number of top-mirror pairs has also been studied to determine how cavity design impacts speed and bit energy. Our design and performance predictions paves the way for realizing highly efficient, ultra-small VCSEL arrays with applications in optical interconnects. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Amplified Spontaneous Emission is ubiquitous in systems with optical gain and is responsible for many opportunities and shortcomings. Its role in the progression from the simplest form of thermal radiation (single emitter spontaneous emission) all the way to coherent radiation from inverted systems is still an open question. We critically review observations of photon bursts in micro- and nanolasers, in the perspective of currently used measurement techniques, in relation to threshold-related questions for small devices. Corresponding stochastic predictions are analyzed, and contrasted with burst absence in differential models, in light of general phase space properties. A brief discussion on perspectives is offered in the conclusions.

When entering the phase of big data processing and statistical inferences in experimental physics, the efficient use of machine learning methods may require optimal data preprocessing methods and, in particular, optimal balance between details and noise. In experimental studies of strong-field quantum electrodynamics with intense lasers, this balance concerns data binning for the observed distributions of particles and photons. Here we analyze the aspect of binning with respect to different machine learning methods (Support Vector Machine (SVM), Gradient Boosting Trees (GBT), Fully-Connected Neural Network (FCNN), Convolutional Neural Network (CNN)) using numerical simulations that mimic expected properties of upcoming experiments. We see that binning can crucially affect the performance of SVM and GBT, and, to a less extent, FCNN and CNN. This can be interpreted as the latter methods being able to effectively learn the optimal binning, discarding unnecessary information. Nevertheless, given limited training sets, the results indicate that the efficiency can be increased by optimizing the binning scale along with other hyperparameters. We present specific measurements of accuracy that can be useful for planning of experiments in the specified research area.