{"id":77818,"date":"2026-04-02T08:50:46","date_gmt":"2026-04-02T06:50:46","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=77818"},"modified":"2026-04-03T13:58:32","modified_gmt":"2026-04-03T11:58:32","slug":"ultra-confined-terahertz-waves","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/newsletter\/ultra-confined-terahertz-waves.html","title":{"rendered":"Ultra-confined terahertz waves"},"content":{"rendered":"<section  class='av_textblock_section av-mnee40a2-47197878d0a745d1504672cc2ea74e08'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h2 style=\"text-align: center; line-height: 30pt;\"><span style=\"color: #e05624;\">Ultra-confined terahertz waves<\/span><\/h2>\n<\/div><\/section>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-mneexonv-d272d8f23f2d908fbe1f5b3a996ed4b2\">\n#top .hr.av-mneexonv-d272d8f23f2d908fbe1f5b3a996ed4b2{\nmargin-top:20px;\nmargin-bottom:30px;\n}\n.hr.av-mneexonv-d272d8f23f2d908fbe1f5b3a996ed4b2 .hr-inner{\nwidth:500px;\nborder-color:#e05624;\nmax-width:45%;\n}\n.hr.av-mneexonv-d272d8f23f2d908fbe1f5b3a996ed4b2 .av-seperator-icon{\ncolor:#e05624;\n}\n<\/style>\n<div  class='hr av-mneexonv-d272d8f23f2d908fbe1f5b3a996ed4b2 hr-custom  avia-builder-el-1  el_after_av_textblock  el_before_av_one_half  hr-center hr-icon-yes'><span class='hr-inner inner-border-av-border-fat'><span class=\"hr-inner-style\"><\/span><\/span><span class='av-seperator-icon' aria-hidden='true' data-av_icon='\ue808' data-av_iconfont='entypo-fontello'><\/span><span class='hr-inner inner-border-av-border-fat'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<div  class='flex_column av-s6g0g6-067ebddec9acc18e9731c5b8dfc22075 av_one_half  avia-builder-el-2  el_after_av_hr  el_before_av_one_half  first flex_column_div'     ><section  class='av_textblock_section av-mneeee81-3e5a6fd2acadd3fb80612ecb912b08e4'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><p style=\"text-align: justify;\"><a href=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-77814 aligncenter\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel.jpg\" alt=\"\" width=\"450\" height=\"455\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel.jpg 600w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel-297x300.jpg 297w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel-80x80.jpg 80w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel-12x12.jpg 12w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2026\/04\/visuel-36x36.jpg 36w\" sizes=\"auto, (max-width: 450px) 100vw, 450px\" \/><\/a><\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-12jdxv7-53d3f52585b155077c41a3204d6f0d2d\">\n.av_font_icon.av-12jdxv7-53d3f52585b155077c41a3204d6f0d2d{\ncolor:#e05624;\nborder-color:#e05624;\n}\n.av_font_icon.av-12jdxv7-53d3f52585b155077c41a3204d6f0d2d .av-icon-char{\nfont-size:20px;\nline-height:20px;\n}\n<\/style>\n<span  class='av_font_icon av-12jdxv7-53d3f52585b155077c41a3204d6f0d2d avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue89a' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p style=\"text-align: justify;\">Terahertz (THz) waves fall within the range of electromagnetic frequencies between the radio waves used by our cell phones (microwaves) and infrared light (emitted by hot objects, for example). They are being considered for the development of future ultra-high-speed communication systems, such as 6G, as well as for imaging (e.g., security) and molecular detection [1].<br \/>\n<strong><span style=\"color: #e05624;\">In this work [2], we demonstrated a record reduction in the wavelength of THz waves by a factor of several hundred when they propagate through very thin lead iodide (PbI\u2082) crystals (a few hundred nanometers thick). The wavelengths are then reduced to a few micrometers.<\/span><\/strong><\/p>\n<\/div><\/section><\/div>\n<div  class='flex_column av-1tmjtlf-242426c34fdf8072f5580c7d169eb535 av_one_half  avia-builder-el-5  el_after_av_one_half  avia-builder-el-last  flex_column_div'     ><section  class='av_textblock_section av-mnh3jglc-44ec91c1746b91507a3bd56674d68643'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-12jdxv7-3-73ef33b2236b11b8df2c62bd9553fdd9\">\n.av_font_icon.av-12jdxv7-3-73ef33b2236b11b8df2c62bd9553fdd9{\ncolor:#e05624;\nborder-color:#e05624;\n}\n.av_font_icon.av-12jdxv7-3-73ef33b2236b11b8df2c62bd9553fdd9 .av-icon-char{\nfont-size:20px;\nline-height:20px;\n}\n<\/style>\n<span  class='av_font_icon av-12jdxv7-3-73ef33b2236b11b8df2c62bd9553fdd9 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue89a' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p style=\"text-align: justify;\">Observing these waves required the development of a specialized \u201cnear-field\u201d microscope operating in the THz range. The key component of such a microscope is a metal tip illuminated by the focused beam of a THz laser. This tip acts as a small antenna, concentrating the THz wave at its tip. The tips we used were fabricated at the IEMN\u2019s micro-nanofabrication platform by the company Vmicro [3]. To explain the extreme compression of the observed wavelengths, one must take into account the very distinctive layered atomic structure of PbI\u2082 crystals. In these crystals, THz waves exhibit very different properties depending on whether they propagate in the plane of the layers or perpendicular to them. This difference is amplified by the fact that at the THz frequencies used in our microscope, the lead and iodine atoms are vibrating so strongly that the THz photons become very strongly coupled to the atomic vibrations; these are referred to as \u201cpolaritons.\u201d Since PbI\u2082 crystals are only a few tens of micrometers in size, we were able to observe oscillations in the image, proving the existence of ultra-confined polaritons (see figure). Simulations and additional measurements were carried out in collaboration with the CNPEM in Brazil, which confirmed the interpretation of these images.<\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-12jdxv7-2-fe67bac64febd52a309d9c2cc7a07f34\">\n.av_font_icon.av-12jdxv7-2-fe67bac64febd52a309d9c2cc7a07f34{\ncolor:#e05624;\nborder-color:#e05624;\n}\n.av_font_icon.av-12jdxv7-2-fe67bac64febd52a309d9c2cc7a07f34 .av-icon-char{\nfont-size:20px;\nline-height:20px;\n}\n<\/style>\n<span  class='av_font_icon av-12jdxv7-2-fe67bac64febd52a309d9c2cc7a07f34 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue842' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/h5>\n<p style=\"text-align: justify;\"><strong><span style=\"color: #e05624;\">These observations, made for the first time in the THz range for this type of polariton, open the door to new components for processing and controlling THz waves, such as waveguides, modulators, and very small antennas compatible with on-chip integration.<\/span><\/strong><\/p>\n<h5>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-12jdxv7-1-626da4e300ff6ffc5a7de667ef34cd6e\">\n.av_font_icon.av-12jdxv7-1-626da4e300ff6ffc5a7de667ef34cd6e{\ncolor:#e05624;\nborder-color:#e05624;\n}\n.av_font_icon.av-12jdxv7-1-626da4e300ff6ffc5a7de667ef34cd6e .av-icon-char{\nfont-size:25px;\nline-height:25px;\n}\n<\/style>\n<span  class='av_font_icon av-12jdxv7-1-626da4e300ff6ffc5a7de667ef34cd6e avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue826' data-av_iconfont='entypo-fontello' ><\/span><\/span><a href=\"https:\/\/www.doi.org\/10.1038\/s41467-026-69027-6\" target=\"_blank\" rel=\"noopener\"><span style=\"color: #e05624;\">Learn more<\/span><\/a><\/h5>\n<hr \/>\n<p><em>[1] La r\u00e9volution des ondes t\u00e9rahertz, Julien Bourdet, CNRS le Journal, d\u00e9cembre 2020.<br \/>\n[2] Santos, C.N., Feres, F.H., Hannotte, T.\u00a0et al. High quality-factor terahertz phonon-polaritons in layered lead iodide. Nature Communications (2026). <a href=\"https:\/\/doi.org\/10.1038\/s41467-026-69027-6\" target=\"_blank\" rel=\"noopener\">https:\/\/doi.org\/10.1038\/s41467-026-69027-6<\/a><br \/>\n[3] vmicroafmprobes.com<br \/>\n[4] Centro Nacional de Pesquisa em Energia e Materials (CNPEM), Campinas, S\u00e3o Paulo, Brasil<\/em><\/p>\n<p><span style=\"color: #f16728;\"><strong>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-u7hwgj-619e047e1720962866f92ebbef9257af\">\n.av_font_icon.av-u7hwgj-619e047e1720962866f92ebbef9257af{\ncolor:#f16728;\nborder-color:#f16728;\n}\n.av_font_icon.av-u7hwgj-619e047e1720962866f92ebbef9257af .av-icon-char{\nfont-size:25px;\nline-height:25px;\n}\n<\/style>\n<span  class='av_font_icon av-u7hwgj-619e047e1720962866f92ebbef9257af avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue805' data-av_iconfont='entypo-fontello' ><\/span><\/span><\/strong><\/span>Contact : jean-francois.lampin<img loading=\"lazy\" decoding=\"async\" class=\"align=absbottom wp-image-73335 size-full\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6.png\" alt=\"\" width=\"16\" height=\"14\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6.png 16w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2025\/05\/arobase6-14x12.png 14w\" sizes=\"auto, (max-width: 16px) 100vw, 16px\" \/>iemn.fr<\/p>\n<\/div><\/section><\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[297],"tags":[],"class_list":["post-77818","post","type-post","status-publish","format-standard","hentry","category-newsletter"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/77818","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=77818"}],"version-history":[{"count":4,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/77818\/revisions"}],"predecessor-version":[{"id":77850,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/77818\/revisions\/77850"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=77818"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=77818"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=77818"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}