High‑quality nonlinear optical and laser crystals for IR and THz bands

Baga₂gese₆ crystal: characteristics, properties and application in nonlinear optics

Nonlinear Crystal BaGa2GeSe6: Properties & Research

1. General information about the BaGa₂GeSe₆ (BGGSe) crystal

In 2016, a new nonlinear crystal of high optical quality — BaGa₂GeSe₆ (BGGSe) — was obtained for the first time in the world.

Key characteristics:

nonlinear coefficients:
d11=23,6 pm/V;
d22=18,5 pm/V;
d31=18,3 pm/V;
transmission range: 0,522–18 µm;
bandgap width: 2,38 eV;
laser radiation resistance: 5,35 J/cm2.

2. Advantages and prospects of BGGSe usage

BGGSe is a nonlinear material that attracts attention for:

broadband frequency mixing;
ultrashort pulse generation.

Reasons for scientific interest:

relatively low dispersion;
high damage threshold.

Experimental results:

pulse generation in the mid‑IR range with octave coverage up to 18 µm;
a 2,6 -mm‑long crystal provides:
pulse energy of 21 pJ at a frequency of 100 MHz;
spectral transmission band from 5,8 to 8,5 µm;
pulse duration of 91 fs (less than four optical octaves).

3. Compact light source

Features:

provides simultaneous emission across seven frequency octaves (from terahertz to ultraviolet range);
five orders of magnitude brighter than synchrotron sources;
promising for hyperspectral spectroscopy and imaging in medical and environmental research.

Three key components of the system (according to Jens Biegert, OSA scientist, ICFO — Institut de Ciències Fotoniques, Spain):

Ultrafast mid‑infrared light source.
Specially designed photonic‑crystal fiber.
BaGa₂GeSe₆ crystal.

4. Experimental setup and radiation generation process

Radiation generation stages:

Radiation creation using ultrashort mid‑IR laser pulses fed into an optical parametric chirped‑pulse amplifier.
Radiation passage through a photonic‑crystal fiber:

fiber length: 20 cm;
inner diameter: 92 µm;
located inside an argon‑filled chamber;
gas pressure varies from 20 to 35 bar (most efficient dispersive wave generation occurs at 25 bar).

Radiation hitting the BaGa₂GeSe₆ crystal:

crystal thickness: 2,6 mm;
difference‑frequency generation;
spectrum broadening from 340 to 40 000 nm.

Comparison with analogues: the BaGa₂GeSe₆ crystal, developed at the Laboratory of Advanced Technologies, outperformed GaSe and ZnGeP₂ in terms of overall quality factor.

5. Results and scientific prospects

Achieved parameters:

peak power in the ultraviolet range: up to 2,5 MW;
power in the THz range: up to 1,8 MW;
intensity in the ultraviolet and terahertz ranges: up to TW/cm2.

Opportunities enabled by the results:

continuous tuning of radiation from ultraviolet to terahertz range (spectrum width — seven octaves);
application of multimodal measurement techniques in:
molecular spectroscopy;
physical chemistry;
solid‑state physics.

Promising research directions:

investigation of attosecond force fields;
visualization of electrons in crystal lattices and study of their interactions;
study of phase transitions;
superconductivity research;
development of topological physics.

Conclusion: the development of the BaGa₂GeSe₆ crystal and the compact light source using it represents a significant scientific breakthrough, opening new opportunities in nonlinear spectroscopy, imaging, and fundamental research.

Advantages over analogues

Compared to other mid‑IR nonlinear crystals (e.g., AgGaSe2, BaGa4Se7, ZnGeP2), BaGa2GeSe6 offers:

a wider transparency range — it extends further into the long‑wavelength IR region;
a high damage threshold — enhanced resistance to laser irradiation;
good thermal properties — stable operation at high average powers;
efficient phase matching — support for both Type I and Type II across a broad spectrum;
temperature tunability — the ability to adjust phase matching via temperature control;
mechanical stability — easier to process and handle than hygroscopic materials.

Review of key scientific articles

Year	Authors and journal	Topic	Result	Significance/application
2025	Suleymanova et al., UltrafastLight 2025	Generation of narrowband THz radiation in BaGa2GeSe6 and BaGa2GeS6	Successful demonstration of THz radiation generation	Opens pathways for THz spectroscopy and communications
2024	Erushin et al., Optical Materials	Measurement of nonlinear refractive index and absorption coefficients	Quantitative assessment of nonlinear optical properties	Enables design of high‑intensity mid‑IR systems
2024	Kostyukova et al., Photonics	Review of barium chalcogenide crystals	Systematisation of data on BaGa2GeSe6, comparison with analogues	—
2023	Chen et al., Optica Nonlinear Optics Topical Meeting	Narrowband OPO in BaGa2GeSe6 within an intracavity cascade	Efficient generation of narrowband mid‑IR radiation	—
2021	Elu et al., Nature Photonics	7‑octave high‑brightness source with stable phase envelope (340–40 000 nm)	BGGS as part of a nonlinear conversion chain	Enables ultra‑broadband spectroscopy and metrology
2020	Kato et al., Optics Letters	Effective nonlinearity of BaGa2GeSe6	High nonlinearity confirmed for mid‑IR applications	—
2018	Baudisch et al.	Sub‑8‑cycle tunable pulses (4–12 µm) based on OPA with BGGS	Mid‑IR source with high repetition rate (100 kHz)	—
2019	Ionin et al., Optics Express	Frequency conversion up to 12–20 µm using BGGS	Extension of mid‑IR range beyond 12 µm	—
2018–2019	Kato et al., Applied Optics	Formulas for phase matching and thermo‑optic dispersion	Critical data for designing BGGS‑based devices	—
2018	Badikov et al., Optical and Quantum Electronics	SHG of CO laser radiation in BGGS and GaSe	High conversion efficiency in the mid‑IR range	—
2021	Petrov et al., J. Opt. Soc. Am. B	Characterisation of barium nonlinear crystals for the mid‑IR range	Comprehensive review of BGGS properties and potential	—

Picture 30. Optical element BaGa2GeSe6

In 2016, for the first time in the world, a new nonlinear crystal of high optical quality BaGa2GeSe6 (BGGSe, Picture 30) was obtained, which has nonlinearity coefficients d₁₁ = 23.6, d₂₂ = 18.5, d₃₁ = 18.3 pm/V. Transmission range 0.522–18 microns, band gap 2.38 eV, resistance to laser radiation 5.35 J/cm2.
BGGSe is a nonlinear material that is attractive for high—frequency mixing and generation of ultrashort pulses due to its comparatively low dispersion and high damage threshold. Experimental studies show the ability of the material to generate pulses in the mid-IR range with an octave coverage of up to 18 microns. From the first experiment, it can be seen that a 2.6 mm long BGGSe crystal gives a pulse energy of 21 PJ at a frequency of 100 MHz with a spectral bandwidth from 5.8 to 8.5 microns and a pulse duration of 91 fs, which corresponds to less than four optical octaves and confirms the prospects of using this material to create ultrashort generation pulses.
New unique results on parametric transformations of laser radiation at BGS are presented in the articles. Many optical experiments require a wide range of laser frequencies, laser coherence, and high brightness. Desktop lasers and large synchrotron installations cannot meet all these requirements. Currently, a compact light source has been developed that provides simultaneous radiation in seven frequency octaves — from terahertz to the ultraviolet range. A desktop light source provides five orders of magnitude more brightness than synchrotron sources, and can become an important tool for hyperspectral spectroscopy and imaging in medical and environmental research. According to the head of the group, OSA researcher Jens Bigert from ICFO (Institut de Ciences Fotoniques), Barcelona Institute of Science and Technology, Spain, the desktop system would not work without three main components: an ultrafast mid-infrared light source, a specially designed photonic crystal fiber and a BaGa2GeSe6 crystal.

Picture 31. Comparison of the IP-DFG process at a pressure of 25 bar between ZGP, BGGSe and GaSe crystals

In the experimental setup, radiation was generated using ultrashort laser pulses of the mid-IR range supplied to an optical parametric amplifier of chirped pulses. The radiation then passed through a 20 cm long photonic crystal fiber with antiresonance reflection, developed by a group that includes OSA employee Philip St. J. Russell, Max Planck Institute for the Science of Light and Friedrich—Alexander University, Germany. A hollow fiber with an inner diameter of 92 microns was located inside a chamber filled with argon. A change in gas pressure from 20 to 35 bar changed the generation of solitons and dispersion waves in the system. A pressure of 25 bar provides the most efficient generation of dispersion waves. Next, the radiation fell on a 2.6 mm thick BaGa2GeSe6 crystal, on which the difference frequency was generated, diluting the radiation spectrum from 340 to 40,000 nm. The BaGa2GeSe6 optical element, developed in the Laboratory of the Latest Technologies, surpassed GaSe and ZnGeP2 in terms of efficiency in this device in terms of the best combined quality factor.
Regulation of the pressure in the fiber pump allows not only to change the spectral intensity depending on the experimental conditions, but also to obtain peak power in ultraviolet up to 2.5 MW, and power in THz up to 1.8 MW, which opens up completely new prospects for nonlinear and multidimensional spectroscopy. The seven-octave coherent radiation spectrum provides continuous tuning of radiation from ultraviolet to the terahertz range and makes it possible to use new multimodal measurement techniques, for example, in molecular spectroscopy, physical chemistry or solid state physics. For the first time, high peak power made it possible to achieve intensity values in the ultraviolet and terahertz spectral ranges, measured in TW/cm2, which makes it possible to study attosecond force fields and study new phenomena such as the visualization of electrons in crystal lattices and their interactions, phase transitions, superconductivity or topological physics. These scientific works are a breakthrough in science and in the creation of new technologies for the development of mankind.

Scientific articles on the properties and research of the BaGa2GeSe6 Nonlinear crystal

1. D. Z. Suleimanova, Ekaterina Migal, Dmitry Badikov, Fedor Potemkin; Generation of narrowband terahertz radiation in novel quaternary BaGa2GeS6 and BaGa2GeSe6 crystals. Conference: IX International Conference on Ultrafast Optical Science UltrafastLight-2025, At: Lebedev Physical Institute, Moscow, Sep 2025.

https://www.researchgate.net/publication/400 430 932

2. E.Y. Erushin, A.A. Boyko, G.S. Shevyrdyaeva, D.V. Badikov, N.Y. Kostyukova. Measurement of nonlinear refraction and absorption coefficient in BaGa2GeSe6 crystal. Optical Materials, Volume 154, 2024, 115 745, ISSN 0925−3467,

https://doi.org/10.1016/j.optmat.2024.115 745

3. Kostyukova, N.; Erushin, E.; Boyko, A.; Shevyrdyaeva, G.; Badikov, D. Barium Chalcogenide Crystals: A Review. Photonics 2024, 11, 281.

https://doi.org/10.3390/photonics11030281

4. U. Elu, L. Maidment, L. Vamos, J. Poborska, I. Tyulnev, F. Tani, D. Novoa, M. H. Frosz, V. Badikov, D. Badikov, V. Petrov, P. S. J. Russell, and J. Biegert, "High-brightness 7-octave spanning CEP-stable ultrafast source," in High-Brightness Sources and Light-Driven Interactions Congress, Technical Digest Series (Optica Publishing Group, 2024), paper MTu2C.5.

https://doi.org/10.1364/MICS.2024.MTu2C.5

5. W. Chen, L. Wang, I. B. Divliansky, V. Pasiskevicius, O. Mhibik, K. M. Moelster, A. Zukauskas, L. B. Glebov, V. V. Badikov, D. V. Badikov, and V. Petrov, "Narrowband BaGa2GeSe6 Optical Parametric Oscillator Pumped in an Intracavity Cascade Configuration," in Optica Nonlinear Optics Topical Meeting 2023, Technical Digest Series (Optica Publishing Group, 2023), paper Th1B.5.

https://doi.org/10.1364/NLO.2023.Th1B.5

6. U. Elu, L. Maidment, L. Vamos, J. Poborska, I. Tyulnev, F. Tani, D. Novoa, M. H. Frosz, V. Badikov, D. Badikov, V. Petrov, P. S. J. Russell, and J. Biegert, "High brightness 7-octave-spanning coherent light source," in Optica Advanced Photonics Congress 2022, Technical Digest Series (Optica Publishing Group, 2022), paper ATu4A.1.

https://doi.org/10.1364/ASSL.2022.ATu4A.1

7. U. Elu, L. Maidment, L. Vamos, F. Tani, D. Novoa, M. H. Frosz, V. Badikov, D. Badikov, V. Petrov, P. S. J. Russell, and J. Biegert, "7-octave high-brightness CEP-stable light source," in Conference on Lasers and Electro-Optics, Technical Digest Series (Optica Publishing Group, 2022), paper SF4H.2.

https://doi.org/10.1364/CLEO_SI.2022.SF4H.2

8. U. Elu, L. Maidment, L. Vamos, F. Tani, D. Novoa, M. H. Frosz, V. Badikov, D. Badikov, V. Petrov, P. S. J. Russell, and J. Biegert, "High-brightness CEP-stable light source with coverage from 340 nm to 40,000 nm," in Optica High-brightness Sources and Light-driven Interactions Congress 2022, Technical Digest Series (Optica Publishing Group, 2022), paper MTh5C.4.

https://doi.org/10.1364/MICS.2022.MTh5C.4

9. Elu et al., "340 — 40,000 nm coherent light source," 2021 IEEE Photonics Conference (IPC), Vancouver, BC, Canada, 2021, pp. 1−2.

https://doi.org/10.1109/IPC48725.2021.9 592 965

10. Valentin Petrov, Valeriy V. Badikov, Dmitrii V. Badikov, Kiyoshi Kato, Galina S. Shevyrdyaeva, Kentaro Miyata, Mark Mero, Li Wang, Zsuzsanna Heiner, and Vladimir L. Panyutin, "Barium nonlinear optical crystals for the mid-IR: characterization and some applications," J. Opt. Soc. Am. B 38, B46-B58 (2021)

https://doi.org/10.1364/JOSAB.425 169

11. Seven-octave high-brightness and carrier envelope phase-stable light source. Elu U., Maidment L., Vamos L., Tani F., Novoa D., Frosz M.H., Badikov V., Badikov D., Petrov V., Russell P.St.J., Biegert J.; Nature Photonics, Volume 15, Issue 4, p.277−280, 2021 (Published: 14 December 2020). DOI: 10.1038/s41566−020−735−1

https://doi.org/10.1038/s41566−020−735−1

12. Barium Nonlinear Optical Crystals for the Mid-IR: Characterization and Applications. Valentin Petrov, Valeriy V. Badikov, Dmitrii V. Badikov, Galina S. Shevyrdyaeva, Kiyoshi Kato, Kentaro Miyata, Konstantin V. Mitin, Li Wang, and Vladimir Panyutin.; OSA High-brightness Sources and Light-driven Interactions Congress 2020 (EUVXRAY, HILAS, MICS) OSA Technical Digest (Optical Society of America, 2020), paper MTu1C.6. DOI: 10.1364/MICS.2020.MTu1C.6

https://doi.org/10.1364/MICS.2020.MTu1C.6

13. Effective Nonlinearity of Trigonal Crystals of Symmetry Class 3 on the Example of the Non-Oxide BaGa2GeSе6. Kentaro Miyata, Kiyoshi Kato, Valeriy V. Badikov, Vladimir L. Panyutin, Li Wang, Konstantin V. Mitin, and Valentin Petrov.; OSA High-brightness Sources and Light-driven Interactions Congress 2020, OSA Technical Digest (Optical Society of America, 2020), paper MTu1C.4. DOI: 10.1364/MICS.2020.MTu1C.4

https://doi.org/10.1364/MICS.2020.MTu1C.4

14. Laser-induced damage threshold of the nonlinear crystals BaGa4Se7 and BaGa2GeSe6 at 2091 nm in the nanosecond regime. Kostyukova N., Boyko A., Eranov I., Antipov O., Kolker D., Kostyukov A., Erushin E., Miroshnichenko I., Badikov D., Badikov V.; Journal of the Optical Society of America B, Vol. 37, No. 9 / September 2020, pp.2655−2659. DOI: 10.1364/JOSAB.396 746

https://doi.org/10.1364/JOSAB.396 746

15. Few-cycle mid-infrared pulses from BaGa2GeSe6. UgaitzElu, Luke Maidment, Lenard Vamos, Tobias Steinle, Florian Haberstroh, Valentin Petrov, Valeriy Badikov, Dmitrii Badikov, and Jens Biegert.; 9th EPS-QEOD Europhoton Conference, 30 August — 04 September 2020; Europhysics Conference Abstract, Volume 44 A, We-A1.3

16. Few-cycle mid-IR pulses by DFG in BaGa2GeSe6. U. Elu, L. Maidment, L. Vamos, T. Steinle, F. Haberstroh, V. Petrov, V. Badikov, D. Badikov, J. Biegert.; Optics Letters, Vol. 45, Issue 13, pp. 3813−3815 (2020). DOI: 10.1364/OL.397 981

https://doi.org/10.1364/OL.397 981

17. Effective nonlinearity of the new quaternarychalcogenide crystal BaGa2GeSе6. Kiyoshi Kato, Valeriy V. Badikov, Li Wang, Vladimir L. Panyutin, Konstantin V. Mitin, Kentaro Miyata, and Valentin Petrov.; Optics Letters, Vol. 45, Issue 8, pp. 2136−2139 (2020), DOI: 10.1364/OL.388 373

https://doi.org/10.1364/ol.388 373

18. Effective Nonlinearity of BaGa2GeSе6: A Promising Quaternary Chalcogenide Crystal for the Mid-IR. Kiyoshi Kato, Valeriy V. Badikov, Li Wang, Vladimir L. Panyutin, Konstantin V. Mitin, Kentaro Miyata, and Valentin Petrov. CLEO Conference 2020, Laser Science to Photonic Applications, San Jose, California, CA, USA, 11−15 May 2020. Paper: SF3R.2.

19. Frequency Down-Conversion of 1 μm Laser Radiation to the Mid-IR using Non-Oxide Nonlinear Crystals in Cascaded Intracavity Configurations. Petrov V., Boyko A., Badikov V., Pasiskevicius V., Kostyukova N., Kolker D., Badikov D., Shevyrdyaeva G., Wang L., Chen W., Panyutin V.; The 12th International Photonics and OptoElectronics Meetings (POEM — 2019), Wuhan, China, November 11−14, 2019, OSA Technical Digest (Optical Society of America, 2019), paper LTh3E.2., DOI: 10.1364/LST.2019.LTh3E.2

https://doi.org/10.1364/LST.2019.LTh3E.2

20. Thermo-optic dispersion formula for BaGa2GeSe6. Kato K., Miyata K., Okamoto T., Badikov V., and Petrov V.; Applied Optics, Vol. 58, No. 35, December 2019, p. 9709−9711. DOI: 10.1364/AO.58.9 709

https://doi.org/10.1364/AO.58.9 709

21. Comparative Analysis of Optical Damage in Advanced Barium Chalcogenides Nonlinear Crystals at 1-μm and 2-μm. Kostyukova N., Boyko A., Eryshin E., Kolker D., Antipov O., Eranov I., Isaenko L., Badikov D. and Badikov V.; The European Conference on Lasers and Electro-Optics 2019, Munich, Germany, 23−27 June 2019, OSA Technical Digest (Optical Society of America, 2019), paper cd_p₁₄

https://doi.org/10.1109/CLEOE-EQEC.2019.8 873 248

22. Frequency conversion of mid-IR lasers into the long-wavelength domain of 12−20 μm with AgGaSe2, BaGa2GeSe6 and PbIn6Te10 nonlinear crystals. A. A. Ionin, I. O. Kinyaevskiy, Yu. M. Klimachev, A. A. Kotkov, A. Yu. Kozlov, A. M. Sagitova, D. V. Sinitsyn, O. A. Rulev, V. V. Badikov, and D. V. Badikov.; Optics Express Vol. 27, Issue 17, pp. 24 353−24 361 (2019). DOI: 10.1364/OE.27.24 353

https://doi.org/10.1364/OE.27.24 353

23. Sum frequency conversion of multiline CO laser emission in BaGa2GeSe6 crystal of one cm long. D V Badikov, V V Badikov, A AIonin, I O Kinyaevskiy, Yu M Klimachev, A AKotkov, V A Mozhaeva, and A M Sagitova.; Journal of Physics: Conference Series, Volume 1189, article ID 12 023 (2019). DOI: 10.1088/1742−6596/1189/1/12 023

https://doi.org/10.1088/1742−6596/1189/1/12 023

24. Few-cycle mid-IR pulses by DFG in BaGa2GeSe6. Ugaitz Elu, Luke Maidment, Lenard Vamos, Tobias Steinle, Florian Haberstroh, Valentin Petrov, Valeriy Badikov, Dmitrii Badikov, and Jens Biegert.; International Conference Ultrafast Optics XII, October 6−11, 2019, Croatia.

25. Laser-Induced Damage Threshold of BaGa4Se7 and BaGa2GeSe6 Nonlinear Crystals at 1.053 μm. Nadezhda Y. Kostyukova, Andrey A. Boyko, Evgenii Y. Erushin, Anton I. Kostyukov, Valeriy V. Badikov, Dmitrii V. Badikov, and Dmitry B. Kolker; Journal of the Optical Society of America B, Vol. 36, Issue 8, pp. 2260−2265 (2019). DIO: 10.1364/JOSAB.36.2 260

https://doi.org/10.1364/JOSAB.36.2 260

26. CO-laser with multi-stage intra- and extra-resonator broadband frequency conversion in BAGA2GES6 crystals (1.7 — 6.0 microns). Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Sagitova A.M., Sinitsyn D.V., Badikov V.V., Badikov D.V.; VIII International Conference on Photonics and Information Optics: collection of Scientific Papers (Moscow, January 23−25, 2019); Moscow; Russia; NRU MEPhI; 2019; pp. 103−104

27. IR active phonons of the BAGA2GES6 nonlinear crystal. Budkin I.V., Klimin S.A., Badikov D.V., Badikov V.V.; VIII International Conference on Photonics and Information Optics: collection of Scientific Papers (Moscow, January 23−25, 2019); Moscow; Russia; NRU MEPhI; 2019; pp. 313 — 314.

28. Lattice dynamics and electronic properties of a BAGA2GES6 nonlinear crystal: Raman scattering, IR reflection, and abinitio calculation. Klimin S.A., Mavrin B.N., Budkin I.V., Badikov V.V., Badikov D.V.; Optics and Spectroscopy: a Scientific Journal, vol. 127, Issue 1.; Saint Petersburg; Russia; A.F. Ioffe Institute of Physics and Technology of the Russian Academy of Sciences; 2019; pp. 20−24; ISSN: 0030−4034.

https://journals.ioffe.ru/articles/47 925

29. Broadband (1.7 — 6.0 µm) multi-frequency CO-laser system with in- and out-of-band frequency conversion in BAGA2GES6 crystals. Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Sagitova A.M., Sinitsyn D.V., Badikov V.V., Badikov D.V.; Applied Optics — 2018: International Conference, Laser Technology, December 19−21, 2018, St. Petersburg; St. Petersburg; Russia; GOI; 2018; p.12/26.

30. Characterization of the BAGA2GES6 crystal by generating the second harmonic and total radiation frequencies from the laser. Mozhaeva V.A., Badikov V.V., Badikov D.V., Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kotkov A.A.; Modern problems of physics and technology: abstracts of the VII-th International Youth Scientific School-Conference, Moscow, April 16−21, 2018 — Part I.; Moscow; Russia; NRU MEPhI; 2018; pp. 156−157.

31. Generation of total radiation frequencies from a laser in a BAGA2GES6 crystal with an intra-resonator conversion option. Sagitova A.M., Badikov V.V., Badikov D.V., Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Mozhaeva V.A., Sinitsyn D.V.; Lasers in science, Technology, medicine: proceedings of the XXIX International Conference (Moscow, May 16−18 2018) / Edited by V.A. Petrov. — Vol. 29; Moscow; Russia; MNTORES named after A.S. Popov; 2018; pp. 81−85.

32. Intra-resonator frequency conversion of radiation from a laser in a BAGA2GES6 crystal. Sagitova A.M., Badikov V.V., Badikov D.V., Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Mozhaeva V.A., Sinitsyn D.V.; Modern problems of physics and technology: abstracts of the VII-th International Youth Scientific School-Conference, Moscow, April 16−21, 2018 — Part I; Moscow; Russia; NRU MEPhI; 2018; pp. 195−196.

33. New BaGa2GeSe6 nonlinear crystal for mid-IR applications. Badikov V.V., Badikov D.V., Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Mozhaeva V.A., Sagitova A.M., Sinitsyn D.V.; Proceedings of the XXV International Scientific and Technical Conference and School on Photovoltaics and Night Vision Devices, Moscow, May 24−26 2018; Moscow; Russia; National Research Nuclear University "MEPhI"; 2018; p. 302.

34. Modeling of broadband frequency conversion of CO laser radiation in a BaGa2GeSe6 nonlinear crystal. Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Mozhaeva V.A., Badikov D.V., Badikov V.V. VII International Conference on Photonics and Information Optics: Collection of Scientific Papers, Moscow, January 24−26, 2018; Moscow; Russia; National Research Nuclear University "MEPhI"; 2018; pp. 312−313.

35. Intra-resonator generation of total radiation frequencies from a laser in a BAGA2GES6 crystal. Badikov V.V., Badikov D.V., Ionin A.A., Kinyaevsky I.O., Klimachev Yu.M., Kozlov A.Yu., Kotkov A.A., Mozhaeva V.A., Sagitova A.M., Sinitsyn D.V.; Laser, plasma research and technology: LaPlaz-2018: proceedings of the IV International Conference, Moscow, January 30 — February 1, 2018; Moscow; Russia; National Research Nuclear University "MEPhI"; 2018; p. 473.

36. Intracavity frequency conversion of multilineCO laser radiation in nonlinear crystal BaGa2GeSe6. Yu.M. Klimachev, V.V. Badikov, D.V. Badikov, A.A. Ionin, I.O. Kinyaevskiy, A.A. Kotkov, A.Yu.Kozlov, A.M. Sagitova, D.V. Sinitsyn.; International Conference Laser Optics 2018, ICLO 2018, St. Petersburg; Russia, 4 June-8 June 2018, Proceedings p. 83. DOI: 10.1109/LO.2018.8 435 742

https://doi.org/10.1109/LO.2018.8 435 742

37. Sum frequency generation of multi-line slabradio frequency discharge carbon monoxide laser system with intracavity nonlinearBaGa2GeSe6 crystal. Ionin, A.A., Badikov, D.V., Badikov, V.V., Kinyaevskiy, I.O., Klimachev, Yu.M., Kotkov, A.A., Kozlov, A.Yu., Sagitova, A.M., Sinitsyn, D.V.; Optics Letters, Vol. 43, No. 18, p.4358−4361, 15 September 2018. DOI: 10.1364/OL.43.4 358

https://doi.org/10.1364/OL.43.4 358

38. Phase-matching properties of BaGa2GeSe6 for three wave interactions in the 0.778−10.5910 μm spectral range. Kiyoshi Kato, Kentaro Miyata, Valeriy V. Badikov, and Valentin Petrov.; Applied Optics, Vol. 57, Is. 26, 2018, p. 7440−7443. DOI: 10.1364/AO.57.7 440

https://doi.org/10.1364/AO.57.7 440

39. Sum-frequency generation of Q-switched CO laserradiation in BaGa2GeSe6 and GaSe nonlinear crystals. Dmitriy V. Badikov, Valeriy V. Badikov, Andrey A. Ionin, Igor O. Kinyaevskiy, Yury M. Klimachev, Andrey A. Kotkov, Konstantin V. Mitin, Daria V. Mokrousova and Vera A. Mojaeva.; Optical and Quantum Electronics 50(6), May 2018. DOI: 10.1007/s11082−018−1514−0

https://doi.org/10.1007/s11082−018−1514−0

40. Sub-8 optical cycle, 4−12 μm tunable, μJ-level pulse generation via a BaGa2GeSe6-based, 1.96 μm pumped OPA at 100 kHz. Matthias Baudisch, Marcus Beutler, Martin Gebhardt, Christian Gaida, Fabian Stutzki, Steffen Hädrich, Robert Herda, Valeriy Badikov, Dmitrii Badikov, Valentin Petrov, Armin Zach, Jens Limpert, and Ingo Rimke.; XXI INTERNATIONALONFERENCE ON ULTRAFASTPHENOMENA, Topical meeting and tabletop exhibit, Hamburg, Germany, July 15 -20, 2018, Europhysics Conference Abstracts Volume 42B ISBN N° 979−10−96 389−09−4. Oral WED.3B.2 15:45.

41. Femtosecond mid-IR difference-frequency generation in BaGa2GeSe6 from a 40 MHz optical parametric oscillator pumped at 1035 nm. Gero Stibenz, Marcus Beutler, Ingo Rimke, Valeriy Badikov, Dmitrii Badikov, Valentin Petrov.; CLEO: Science and Innovations 2018, San Jose, California United States, 13−18 May 2018; OSA Technical Digest (online) (Optical Society of America, 2018), paper STh4 °F.5. DOI: 10.1364/CLEO_SI.2018.STh4 °F.5.

https://doi.org/10.1364/CLEO_SI.2018.STh4 °F.5

42. Intracavity-pumped, cascaded optical parametric oscillatorbased on baga2ges6. Andrey Boyko, Valeriy Badikov, Galina Shevyrdyaeva, Dmitrii Badikov, Valdas Pasiskevicius, Andrius Zukauskas, Valentin Petrov.; Mid-Infrared Coherent Sources 2018, Strasbourg France, 26−28 March 2018; OSA Technical Digest (online) (Optical Society of America, 2018), paper MW2C.3. DOI: 10.1364/MICS.2018.MW2C.3

https://doi.org/10.1364/MICS.2018.MW2C.3

43. Generation of total CO laser radiation frequencies in nonlinear GaSe and BaGa2GeSe6 crystals. Sagitova A.M., Badikov D.V., Badikov V.V., Ionin A. A., Kinyaevsky I.O., Klimachev Yu.M., Kotkov A.A., Mitin K.V., Mokrousova D. V., Mozhaeva V.A.; Physics. St. Petersburg/2017: Abstracts of the International Conference, St. Petersburg, October 24−26, 2017; St. Petersburg; Russia; 2017; pp. 204−205.

44. Conversion of Sum Frequencies in GaSe and BaGa2GeSe6 Nonlinear Crystals of Multi-Line Q-Switched CO Laser Radiation. D Badikov, V Badikov, AIonin, I Kinyaevskiy, Yu Klimachev, A Kotkov, D Mokrousova, and V Mojaeva.; 26th ANNUAL INTERNATIONAL LASER PHYSICS WORKSHOP (LPHYS'17), (Kazan, July 17−21, 2017), Endorsed by the Optical Society of America (OSA).

http://www.lasphys.com/workshops/lasphys17/program-seminar-5