Научная статья на тему 'Nonlinear absorption and refraction study of quaternary barium chalcogenide BaGa2GeSe6 crystal at 1053 nm in nanosecond regime'

Nonlinear absorption and refraction study of quaternary barium chalcogenide BaGa2GeSe6 crystal at 1053 nm in nanosecond regime Текст научной статьи по специальности «Медицинские технологии»

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Текст научной работы на тему «Nonlinear absorption and refraction study of quaternary barium chalcogenide BaGa2GeSe6 crystal at 1053 nm in nanosecond regime»

The 30th International Conference on Advanced Laser Technologies LS-O-9

ALT'23

Nonlinear absorption and refraction study of quaternary barium chalcogenide BaGa2GeSe6 crystal at 1053 nm in nanosecond regime

N. Kostyukova1'2' *, E. Erushin1'2, A. Boyko1'2, A. Kostyukov1, A. Kiryakova2, D. Badikov3

1-Novosibirsk State University, Russia, 630090, Novosibirsk, 1, Pirogova str.

2- Institute of Laser Physics of the SB of the RAS, Russia, 630090, Novosibirsk, prosp. Ac. Lavrentiev, 15B 3- Kuban State University, 149 Stavropolskaya Str., 350040 Krasnodar, Russia

* n. [email protected]

Barium chalcogenide crystals are promising nonlinear media for efficient parametric down-conversion in the mid-IR range [1]. Nonlinear absorption and refraction that occur in crystals upon interaction with high-power laser radiation can lead to distortion of the transverse distribution of the laser beam intensity in the crystal and the occurrence of self-focusing effects and mismatch of the optical cavity, and thereby reduce the efficiency of conversion. Therefore, it is important to take them into account when designing optical set-ups of highly efficient mid-IR tunable optical parametric oscillators (OPOs). This work is devoted to an experimental study of the nonlinear optical characteristics of the BaGa2GeSe6 (BGGSe) crystal by Z-scan technique proposed in the work [2].

The radiation source was a diode-pumped Q-switched Nd:YLF laser produced pulses with a duration of 6 ns and energy up to 1 mJ at 1.053 ^m with repetition rate varied from 0.1 to 4 kHz. The measured beam quality factor M2 was around 1.4 and the radiation's linewidth was 227 pm (approximately 2 cm-1). The BGGSe plate was cut at 9=30° and 9=30° with wedge of all plates was no more than 10 arc seconds. The surface quality can be estimated as 60-40 scratch and dig, and surface flatness was A/6 at 633 nm. The both sides of tested plate have an AhO3 antireflection (AR) coating centered at 1053 nm. Measured P and n2-values in the BGGSe plate with nanosecond 1053 nm laser pulses at different intensity are presented in Table 1.

Table 1. Measured P and n2-values in the BGGSe plate with nanosecond 1053 nm laser pulses at 1 kHz

I, MW/cm2 Pol. ß, cm/GW n2Xl0-13, cm2/W n2X10-10, esu

49,3 e-wave 5,59 5,79 3,615

o-wave - 3,34 3,34

84 e-wave 6,58 9,37 5,85

o-wave 4,7 7,53 4,55

117 e-wave 6,71 12,57 7,86

o-wave 5,08 9,93 5,68

A strong dependence of nonlinear absorption and refraction on the radiation intensity is observed. This may be related to thermal effects, which are most appeared at nanosecond pulses [3].

This work was supported by the Russian Science Foundation (Project no. 23-22-00368).

[1] V. Petrov, V. Badikov, D. Badikov, K. Kato, G.Shevyrdyaeva, K. Miyata, M. Mero, L. Wang, Z. Heiner, V. Panyutin, Barium nonlinear optical crystals for the mid-IR: characterization and some applications, J. Opt. Soc. Am. B, vol. 38, pp. B46-B58, (2021).

[2] M. Sheik-Bahae, A. A. Said, E. W. Van Stryland. High-sensitivity, single-beam n2 measurements, Opt. Lett., vol. 14, p. 955 (1989).

[3] T. Olivier, F. Billard, and H.Akhouayri, Z-scan theoretical and experimental studies for accurate measurements of the nonlinear refractive index and absorption of optical glasses near damage threshold, Proc. SPIE 5273, Laser-Induced Damage in Optical Materials: 2003, (10 June 2004).

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