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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="ru"><front><journal-meta><journal-id journal-id-type="publisher-id">ntv</journal-id><journal-title-group><journal-title xml:lang="ru">Научно-технический вестник информационных технологий, механики и оптики</journal-title><trans-title-group xml:lang="en"><trans-title>Scientific and Technical Journal of Information Technologies, Mechanics and Optics</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2226-1494</issn><issn pub-type="epub">2500-0373</issn><publisher><publisher-name>Университет ИТМО</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.17586/2226-1494-2023-23-3-439-447</article-id><article-id custom-type="elpub" pub-id-type="custom">ntv-3</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>ОПТИЧЕСКИЕ СИСТЕМЫ И ТЕХНОЛОГИИ</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>OPTICAL ENGINEERING</subject></subj-group></article-categories><title-group><article-title>Оптические свойства нелинейных кристаллов семейства боратов и их применение в источниках интенсивного терагерцового излучения</article-title><trans-title-group xml:lang="en"><trans-title>Optical properties of borate family nonlinear crystals and their application in sources of intense terahertz radiation</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-3009-762X</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Лубенко</surname><given-names>Д. М.</given-names></name><name name-style="western" xml:lang="en"><surname>Lubenko</surname><given-names>D. M.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Лубенко Дмитрий Михайлович — младший научный сотрудник </p><p>sc 55642871000</p><p>Томск, 634055 </p></bio><bio xml:lang="en"><p>Dmitry M. Lubenko — Junior Researcher </p><p>sc 55642871000 </p><p>Tomsk, 634055 </p></bio><email xlink:type="simple">lubenkodm@gmail.com</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-3311-5088</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Ежов</surname><given-names>Д. М.</given-names></name><name name-style="western" xml:lang="en"><surname>Ezhov</surname><given-names>D. M.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Ежов Дмитрий Михайлович — младший научный сотрудник </p><p>sc 57195325727 </p><p>Томск, 634050 </p></bio><bio xml:lang="en"><p>Dmitry M. Ezhov — Junior Researcher </p><p>sc 57195325727 </p><p>Tomsk, 634050 </p></bio><email xlink:type="simple">ezhov_dm@mail.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-3935-0871</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Светличный</surname><given-names>В. А.</given-names></name><name name-style="western" xml:lang="en"><surname>Svetlichnyi</surname><given-names>V. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Светличный Валерий Анатольевич — кандидат физико-математических наук, доцент, заведующий лабораторией</p><p>sc 35514642000 </p><p>Томск, 634050</p></bio><bio xml:lang="en"><p>Valery A. Svetlichnyi — PhD (Physics &amp; Mathematics), Associate Professor, Head of Laboratory</p><p>sc 35514642000 </p><p>Tomsk, 634050 </p></bio><email xlink:type="simple">v_svetlichnyi@bk.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-1891-9846</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Андреев</surname><given-names>Ю. М.</given-names></name><name name-style="western" xml:lang="en"><surname>Andreev</surname><given-names>Yu. M.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Андреев Юрий Михайлович — доктор физико-математических наук, главный научный сотрудник</p><p>sc 55411777300 </p><p>Томск, 630055 </p></bio><bio xml:lang="en"><p>Yury M. Andreev — D.Sc. (Physics &amp; Mathematics), Chief Researcher </p><p>sc 55411777300 </p><p>Tomsk, 630055 </p></bio><email xlink:type="simple">yuandreev@yandex.ru</email><xref ref-type="aff" rid="aff-3"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-7106-3100</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Николаев</surname><given-names>Н. А.</given-names></name><name name-style="western" xml:lang="en"><surname>Nikolaev</surname><given-names>N. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Николаев Назар Александрович — кандидат технических наук, старший научный сотрудник</p><p>sc 56363884600 </p><p>Новосибирск, 630090 </p></bio><bio xml:lang="en"><p>Nazar A. Nikolaev — PhD, Senior Researcher </p><p>sc 56363884600</p><p>Novosibirsk, 630090</p></bio><email xlink:type="simple">nazar@iae.nsk.su</email><xref ref-type="aff" rid="aff-4"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Институт сильноточной электроники Сибирского отделения Российской академии наук</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-2"><aff xml:lang="ru"><institution>Национальный исследовательский Томский государственный университет</institution><country>Россия</country></aff><aff xml:lang="en"><institution>National Research Tomsk State University</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-3"><aff xml:lang="ru"><institution>Институт мониторинга климатических и экологических систем Сибирского отделения Российской академии наук</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-4"><aff xml:lang="ru"><institution>Институт автоматики и электрометрии Сибирского отделения Российской академии наук</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2023</year></pub-date><pub-date pub-type="epub"><day>10</day><month>12</month><year>2024</year></pub-date><volume>23</volume><issue>3</issue><fpage>439</fpage><lpage>447</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Лубенко Д.М., Ежов Д.М., Светличный В.А., Андреев Ю.М., Николаев Н.А., 2024</copyright-statement><copyright-year>2024</copyright-year><copyright-holder xml:lang="ru">Лубенко Д.М., Ежов Д.М., Светличный В.А., Андреев Ю.М., Николаев Н.А.</copyright-holder><copyright-holder xml:lang="en">Lubenko D.M., Ezhov D.M., Svetlichnyi V.A., Andreev Y.M., Nikolaev N.A.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://ntv.elpub.ru/jour/article/view/3">https://ntv.elpub.ru/jour/article/view/3</self-uri><abstract><p>Введение. Для нелинейных кристаллов семейства боратов характерны высокие значения порога оптического пробоя на длинах волн ближнего инфракрасного диапазона. Как следствие, такие кристаллы являются эффективными генераторами гармоник излучения интенсивных лазерных источников. Последние исследования показали, что нелинейные кристаллы семейства боратов демонстрируют низкое поглощение излучения на субтерагерцовых частотах. Данный факт свидетельствует о возможности их применения в качестве генераторов терагерцового излучения. Выполнено сравнение источников терагерцового излучения на основе преобразования частоты излучения титан-сапфирового лазера в кристаллах бета-бората бария (β-BaB2O4), трибората лития (LiB3O5) и тетрабората лития (Li2B4O7). Метод. Проведен расчет реализуемых типов коллинеарного трехволнового взаимодействия, обеспечивающих генерацию разностной частоты в субтерагерцовом диапазоне с учетом изученной дисперсии главных компонент терагерцового показателя преломления исследованных кристаллов. Для каждого кристалла получены условия фазового согласования и соответствующие длины когерентности. Учитывая тензоры квадратичной восприимчивости, рассчитаны коэффициенты эффективной нелинейности. Выполнены оценка и сравнение эффективности генерации терагерцового излучения в кристаллах с различным срезом. Основные результаты. Результаты расчетов показали, что генерация в кристалле β-BaB2O4 происходит эффективнее на три порядка по сравнению с кристаллом LiB3O5 и на пять — с Li2B4O7. На титансапфировом усилителе экспериментально изучена генерация терагерцового излучения в образце кристалла β-BaB2O4 со срезом θ = 5° (где θ — угол между вектором распространения излучения и главной оптической осью z кристалла), обеспечивающим фазовое согласование для частоты 0,3 ТГц. Сравнение экспериментально полученных данных с численным расчетом показало, что на генерацию излучения оказывают влияние типы взаимодействия o – e → e, e – e → o и o – o → o. При этом значение пиковой мощности терагерцового излучения приблизительно составляет 20 кВт. Обсуждение. Полученные данные будут полезны для разработки генераторов интенсивного излучения субтерагерцового диапазона, основанных на преобразовании энергии мощных лазерных источников. Полученные результаты показали, что увеличение интенсивности оптических полей до предпороговых значений для кристалла β-BaB2O4 позволит достичь десятков гигаватт пиковой мощности терагерцового излучения. Такие источники излучения могут найти применение в системах зондирования атмосферы и ускорителях заряженных частиц.</p></abstract><trans-abstract xml:lang="en"><p>Nonlinear crystals of the borate family are efficient harmonic generators for intense laser sources because of their high laser-induced damage threshold at near-infrared wavelengths. Recent studies have shown that they exhibit relatively low absorption coefficients at sub-terahertz frequencies, which could enable them to generate terahertz radiation. Based on this assumption, we compare terahertz sources based on the frequency down-conversion of the radiation from a titanium-sapphire amplifier in crystals of barium beta-borate (β-BaB2O4), lithium triborate (LiB3O5), and lithium tetraborate (Li2B4O7). The calculation of collinear three-wave interactions, which provide the generation of the subterahertz difference frequency, is carried out considering the previously studied dispersion of the main components of the terahertz refractive index of these crystals. The phase-matching conditions and the corresponding coherence lengths are determined for each of the crystals. Taking into account the quadratic susceptibility tensors, the coefficients of the effective nonlinearity are calculated, and the terahertz generation efficiency in crystals with different cuts is evaluated and compared. The down-conversion in the β-BaB2O4 crystal is numerically shown to be three and five orders of magnitude more efficient than in the LiB3O5 and Li2B4O7 crystals, respectively. Thus, terahertz generation in a sample of β-BaB2O4 crystal with a cut that provides phase-matching for a frequency of 0.3 THz (θ = 5°) has been studied experimentally using radiation from a titanium-sapphire amplifier. The comparison of the experimental data and the numerical results leads to the conclusion that the main contribution to the generation process is given by the o – e → e, e – e → o, and o – o → o types of interaction. The peak terahertz power reaches 20 kW. The data obtained in this work will be useful for the development of intense sub-terahertz radiation sources based on the energy conversion of high-power laser sources. It is estimated that tens of GW of peak terahertz power can be achieved by increasing the intensity of the optical fields to pre-threshold values for the β-BaB2O4 crystal. A source of this intensity can be used in systems for sounding the atmosphere as well as in charged particle accelerators.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>нелинейные кристаллы</kwd><kwd>генерация терагерцовых частот</kwd><kwd>фазовый синхронизм</kwd><kwd>показатель преломления</kwd><kwd>коэффициент поглощения</kwd></kwd-group><kwd-group xml:lang="en"><kwd>nonlinear crystals</kwd><kwd>terahertz frequency generation</kwd><kwd>phase matching</kwd><kwd>refractive index</kwd><kwd>absorption coefficient</kwd></kwd-group><funding-group><funding-statement xml:lang="ru">Исследование выполнено в рамках проектов государственного задания Института автоматики и электрометрии Сибирского отделения Российской академии наук (ИАиЭ СО РАН), проект № 121032400052-6), Института мониторинга климатических и экологических систем Сибирского отделения Российской академии наук, проект № 121031300155-8. Авторы благодарят центр коллективного пользования «Спектроскопия и Оптика» и центр коллективного пользования «ВТАН» Новосибирского государственного университета за предоставленное оборудование.</funding-statement><funding-statement xml:lang="en">The study was carried out within the framework of the State Assignment projects of Institute of Automation and Electrometry of the Siberian branch of the Russian Academy of Sciences (IA&amp;E SB RAS), project No. 121032400052- 6, and Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences, project No. 121031300155-8. The authors express their gratitude to the Shared Equipment Center “Spectroscopy and Optics” of the IA&amp;E SB RAS and the Shared Research Center “VTAN” of the Novosibirsk State University for the provided instrumentation support.</funding-statement></funding-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Wu X., Carbajo S., Ravi K., Ahr F., Cirmi G., Zhou Y., Mücke O.D., Kärtner F.X. Terahertz generation in lithium niobate driven by Ti:sapphire laser pulses and its limitations // Optics Letters. 2014. V. 39. N 18. P. 5403–5406. https://doi.org/10.1364/ol.39.005403</mixed-citation><mixed-citation xml:lang="en">Wu X., Carbajo S., Ravi K., Ahr F., Cirmi G., Zhou Y., Mücke O.D., Kärtner F.X. Terahertz generation in lithium niobate driven by Ti:sapphire laser pulses and its limitations. 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