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4The 30th International Conference on Advanced Laser Technologies ALT'23 \ V
LS-I-12 l\
New spinel-based nanostructured glass-ceramics with broadband absorption of ferrous ions in the spectral range of 1.8-2.4 pm
O. Dymshits1'2, V. Bukina3, K. Trukhanova1, I. Alekseeva2, M. Tsenter2, A. Zhilin5
1-Ioffe Institute, Russian Academy of Sciences, 26 Politekhnicheskaya, 194021 St. Petersburg, Russia 2- S.I. Vavilov State Optical Institute, 36 Babushkina St., 192171 St. Petersburg, Russia 3- Saint Petersburg Mining University, 2 21st Line Vasil'yevski Ostrov, Saint Petersburg, Russia 4- D. V. Efremov Institute of Electrophysical Apparatus, Metallostroy, Doroga na Metallostroy, 3 Bld., 196641 Saint
Petersburg, Russia
Crystals with ferrous ions doped in tetrahedral (Td) sites are promising for saturable absorbers (SAs) of mid-IR lasers because of intense and broad absorption due to the 5E ^ 5T2(5D) transition. ZnS and ZnSe based materials with Td coordinated Fe2+ ions are used as such SAs. Spinel crystals are their good alternatives, as they are ecofriendly, have high hardness, low thermal expansion coefficient and high laser damage threshold. Transparent glass-ceramics (GCs) are multiphase materials in which nanocrystals are uniformly distributed in the residual glass. We present the results of a comparative study of the structure and spectral properties of new transparent GCs based on nanocrystals of y-AkO3, MgAl2O4 and ZnAl2O4 spinels doped with Fe2+ ions.
Initial iron doped glasses of lithium (LAS), magnesium (MAS), and zinc (ZAS) aluminosilicate systems containing TiO2 as a nucleating agent were melted at 1580 °C under reducing conditions. GCs were obtained by heat-treatments in the temperature range of 680 - 1200 °C. Their phase composition and structure were studied by X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC), and Raman spectroscopy. The optical absorption spectra of glasses and GCs were recorded. The initial glasses are X-ray amorphous. During their secondary heat-treatments, lithium-(magnesium-, zinc-) aluminum-titanate regions and "low-silicate" regions enriched in magnesium (zinc) and aluminum are formed, in which crystals with a spinel structure are precipitated, Fig. 1a. Despite the similarity of the processes of phase transformations, the temperature intervals of crystallization of spinel nanocrystals and the character of the titanium-containing phase in these GCs are different, which is manifested in their absorption spectra, Fig. 1b. Absorption spectra are formed by absorption of Fe2+ ions in spinel crystals in Oh and Td positions and by intervalent charge transfer transitions between Fe2+, Fe3+, Ti3+, and Ti4+ ions in spinel and titanium-containing nanocrystals. The structuring of the
Fig. 1. XRD patterns and absorption spectra of spinel-based glass-ceramics of the LAS, MAS and ZAS systems.
The developed transparent glass-ceramics exhibit a broadband absorption in the spectral range of 1.8-2.4 ^m due to the 5E ^ 5T2 (5D) transition of Fe2+ ions in tetrahedral sites in spinel nanocrystals. The glass-ceramics are promising as saturable absorbers of lasers emitting in this spectral range.
This work was partly supported by the Russian Science Foundation (Grant 23-23-00446).
[1] L. Basyrova, V. Bukina, S. Balabanov, et al. Synthesis, structure and spectroscopy of Fe2+:MgAl2O4 transparent ceramics and glass-ceramics, J. Lumin., vol. 236, pp. 118090 (1-17), (2021).
[2] O. Dymshits, V. Bukina, K. Eremeev, et al., Spectral properties and structure of transparent glass-ceramics based on Fe:MgAl2O4 and Fe:ZnAl2O4 crystals, J. Opt. Technol., vol. 88, pp. 323-329 (2021).
[3] K. Eremeev, L. Basyrova, O. Dymshits, Structure and spectral properties of Fe:ZnAl2O4 transparent glass-ceramics and ceramic, J. Phys. Conf. Ser., vol. 2086, pp. 012138 (1-6), (2021).
