The creation of spectrally narrow tunable wavelength over a wide range, having a small loss in laser generation power is an actual problem in modern laser physics. Lasing characteristics (FWHM) of solid state active media based on Chromen 3 (Ch-3) in polymethylmethacrylate (PMMA) are investigated. Patterns of changing the lasing characteristics depending on resonator’s geometric parameters. It is demonstrated that the wavelength of solid state active media in specific resonator's geometric parameters can be narrowed to the lowest value possible. Such laser properties are known for wide application in laser spectroscopy

Nikonova, Elena N.

Solodova, Tatyana A.

Telminov, Evgenii N.

Yacoub, A.

English

Tomsk State University Repository

PULSED LASERS AND LASER APPLICATIONSTHE 15th  INTERNATIONAL CONFERENCEThe 15th International Conference AMPL-2021 PULSED LASERS AND LASER APPLICATIONS September 12–17, 2021 Tomsk, Russia ABSTRACTS GENERAL SPONSOR Special Systems. Photonics, St. Petersburg, Russia CONFERENCE ORGANIZERS Institute of Atmospheric Optics SB RAS Institute of High Current Electronics SB RAS Tomsk State University Tomsk Polytechnic University CONFERENCE SPONSORS Ministry of Education and Science of Russian Federation, Russia Russian Academy of Sciences, Russia Siberian Branch of Russian Academy of Science, Russia Laser Association, Russia  CONFERENCE SPONSORS TOPAZ Research and Inculcation Enterprise, Tomsk, Russia Young Scientists Counsil IAO SB RAS, Tomsk, Russia SP Equipment, Novosibirsk, Russia Azimut Photonics, Moscow, Russia LOTIS TII, Minsk, Belarus Special Systems. Photonics, St.-Petersburg, Russia CLZ Ltd, Moscow, Russia Leningrad Laser Systems, St.-Petersburg, Russia MEDIA SPONSORS Atmospheric and Oceanic Optics Journal, Tomsk, Russia Photonics Journal, Moscow, Russia  Tomsk, 2021  84  LASER SYSTEMS, LASER APPLICATIONS AND NEW LASER AND OPTICAL TECHNOLOGIE SESSION D  D-13 INVESTIGATION OF THE DYNAMICS OF HEATING OF POROUS DIELECTRIC MEDIA MADE OF TRANSPARENT MATERIALS UNDER  THE INFLUENCE OF RADIATION FROM AN YTTERBIUM FIBER LASER V.V. Osipov, E.V. Tikhonov, V.V. Platonov, and V.V. Lisenkov Institute of Electrophysics UB RAS, 106 Amundsen St., 620016, Yekaterinburg, Russia, tikhonov@iep.uran.ru The laser ablation method is actively used today to obtain oxide nanopowders used for the synthesis of optical ceramics and the creation of SOFC cells. Powders such as Y2O3, Al2O3, MgAl2O4, YSZ, etc. have already been synthesized at the IEP UB RAS using a CW ytterbium fiber laser (λ = 1.07 m). These materials, as wide gap dielectrics, have high transparency at λ = 1.07 m. We have already shown that an important role in the evaporation of a target pressed from micron particles is played by the scattering of laser radiation on pores and defects of the crystal structure, which depends on the refractive index of the material n. For example, CaF2 and 1% Nd:Y2O3 have similar absorption indices ( 1–3  10–3 cm–1), but different n (1.43 for CaF2 and 1.90 for Y2O3). At an equal radiation power of a fiber laser of 600 W, the production rate of 1% Nd:Y2O3 nanopowder was 23 g/h, and the CaF2 target did not even evaporate, which is of great scientific and applied interest. The report presents the results of numerical simulation of the pre-ablative stage of heating a target of spherical particles with diameters of 0.4  3 μm at a packing density of  55% by radiation of a fiber laser with an intensity of 0.46 MW/cm2. The numerical model is based on a self consistent solution of the system from the Helmholtz equation and the heat equation. The calculation was carried out for materials with different refractive index n: CaF2 (1.43), Al2O3 (1.75), MgAl2O4 (1.70), Y2O3 (1.90), YSZ (2.12) and ZnSe (2.47). The calculated distribution of the electromagnetic field has a complex structure with local maxima of the radiation intensity, which is associated with the interference of radiation, its reflection and refraction at the boundaries of particles. The radiation intensity at these maxima depends on the diameter of the particles, their refractive index n and the radiation wavelength . Such local maxima can significantly facilitate the initiation of the initial heating of the target material and lead to its further thermal destruction. In the report, using MgAl2O4 as an example, it was shown that the characteristic time during which the material loses its transparency and a laser plume appears is ≈ 40 s. At the initial moment, the temperature linearly increases within 30–35 s to values close to the melting point of the material (2135 C), after which a sharp nonlinear temperature rise begins due to an increase in the concentration of absorbing defects, which ultimately leads to the initiation of ablation. It was found that, with similar thermophysical characteristics, the radiation damage threshold of a powder material can be an order of magnitude lower than for a single crystal of the same material due to the operation of a set of nonlinear mechanisms of interaction of radiation with the target material. The work was performed as part of State Task No. 0389-2019-0003, was supported in part by RFBR Grants Nos. 20-08-00054 À and 20-38-70022. D-14 TUNABLE ORGANIC SOLID STATE LASER A. Yacoub, E.N. Telminov, T.A. Solodova and E.N. Nikonova Tomsk State University, 36 Lenin Ave., 634050, Tomsk, Russia, rector@tsu.ru The creation of spectrally narrow tunable wavelength over a wide range, having a small loss in laser generation power is an actual problem in modern laser physics. Lasing characteristics (FWHM) of solid state active media based on Chromen 3 (Ch-3) in polymethylmethacrylate (PMMA) are investigated. Patterns of changing the lasing characteristics depending on resonator’s geometric parameters. It is demonstrated that the wavelength of solid state active media in specific resonator's geometric parameters can be narrowed to the lowest value possible. Such laser properties are known for wide application in laser spectroscopy.  85  LASER SYSTEMS, LASER APPLICATIONS AND NEW LASER AND OPTICAL TECHNOLOGIE SESSION D   In this paper the laser active media (Ch-3 with concentration 1.10–3 mol/L) was investigated in Littman grating cavity. The main geometric parameters, which have been investigated (l: distance between diffraction grating and the rotating mirror, : the angle between diffraction grating and laser beam generated by lasing active medium). The laser active medium was pumped by second harmonic generation Nd+3:YAG laser ( = 532 nm) where Eg = 3.1 mj. The highest efficiency was achieved when l = 3 cm, and dropped ≈ 5% when l = 9 cm. the narrowest line width was achieved when  = 88 where Δ < 0.018 nm.  1. Minaev B.F. et. al. Computational and Experimental Investigation of the Optical Properties of the Chromene Dyes  // J. Phys. Chem. A. 2015. No. 119. P. 1948−1956. D-15 QUASINEUTRALITY OF THE RELATIVISTIC LASER DRIVEN PROTON BEAM S.N. Andreev1 and V.P. Tarakanov 2 1Moscow Polytechnic University, 38 Bolshaya Semyonovskaya St., 107023, Moscow, Russia, andreev_stepan@mail.ru; 2Joint institute for high temperatures of the RAS, Bd. 2, 13 Izhorskaya St., 125412, Moscow, Russia, karat8tarak@gmail.com Proton beams formed when super intense laser pulses are applied to solid state targets are of great interest for various applications, such as radiography or laser medicine. The bombardment of secondary targets by proton beams can cause nuclear reactions that are promising for fusion  energy [1].  To obtain proton beams with parameters optimized for a specific application, it is necessary to know their properties depending on the parameters of the laser pulse and the target. Many articles and reviews have been devoted to experimental and theoretical studies of laser driven proton beams (see, for example, [2] and the literature cited there). At the same time, only a few papers are devoted to the important question of the quasineutrality of the proton beam. For example, in [3] it was experimentally proved that the proton beam is quasi neutral, which ensures its laminarity and low divergence. However, the dynamics of the formation of a quasi-neutral proton beam has not been investigated. In our work, a computational and theoretical study of the dynamics of the formation of a quasi-neutral proton beam propagating from the rear surface of an aluminum target with a thickness of 10 microns when it is irradiated by a relativistic laser pulse ( = 1,055 m, I = 5  1018 W/cm2,   = 1 ps, angle of incidence 30 degrees) is carried out. The calculations were performed using a two-dimensional XZ version of the fully 3D relativistic electrodynamic PIC code KARAT [4]. From our calculations, it follows that at the initial stage, "hot" electrons accelerated on the front surface of the target pass through the target and form an electrostatic field near its rear surface, in which protons are accelerated. At this stage, the total charge of the beam is negative. Then, the proton current exceeds the electron current, and the total charge of the beam changes sign. Finally, at the third stage, the positive charge of the beam is compensated by "cold" electrons accelerated from the rear surface of the target. The total time to establish the quasineutrality of the proton beam is about two laser pulse durations.  1. Belyaev V.S., Matafonov A.P., Krainov V.P. et al. // Phys. of atomic nuclei. 2020. V. 83. P. 370. 2. Andreev S.N. // Engineering Phys. 2012. V. 6. P. 44. 3. Cowan T.E., Fuchs J., Ruhl H. et al. // Phys. Rev. Let. 2004. V. 92. P. 204801. 4. Tarakanov V.P. // EPJ Web of Conferences. 2017. V. 149. P. 04024. 

Tunable organic solid state laser

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Tunable organic solid state laser

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