{"658072":{"#nid":"658072","#data":{"type":"news","title":"Shaping the Future of Light through Reconfigurable Metasurfaces","body":[{"value":"\u003Cp\u003E\u003Cem\u003EHarnessing the power of \u0026ldquo;phase-change\u0026rdquo; materials, Georgia Tech researchers have demonstrated how reconfigurable metasurfaces \u0026mdash; artificial materials with extraordinary optical properties \u0026mdash; are crucial to the future of nanotechnology.\u003C\/em\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe technological advancement of optical lenses has long been a significant marker of human scientific achievement. Eyeglasses, telescopes, cameras, and microscopes have all literally and figuratively allowed us to see the world in a new light. Lenses are also a fundamental component of manufacturing nanoelectronics by the semiconductor industry.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EOne of the most impactful breakthroughs of lens technology in recent history has been the development of photonic metasurfaces \u0026mdash; artificially engineered nano-scale materials with remarkable optical properties. Georgia Tech researchers at the forefront of this technology have recently demonstrated the first-ever\u0026nbsp;electrically tunable\u0026nbsp;photonic metasurface platform in a recent study published by\u003Cem\u003E\u0026nbsp;\u003Ca href=\u0022https:\/\/www.nature.com\/articles\/s41467-022-29374-6\u0022\u003ENature Communications\u003C\/a\u003E.\u003C\/em\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;Metasurfaces can make the optical systems very thin, and as they become easier to control and tune, you\u0026rsquo;ll soon find them in cell phone cameras and similar electronic imaging systems,\u0026rdquo; said\u0026nbsp;\u003Ca href=\u0022https:\/\/www.ece.gatech.edu\/faculty-staff-directory\/ali-adibi\u0022\u003EAli Adibi\u003C\/a\u003E, professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe pronounced tuning measures achieved through the new platform represent a critical advancement towards the development of miniaturized reconfigurable metasurfaces. The results of the study have shown a record eleven-fold change in the reflective properties, a large range of spectral tuning for operation, and much faster tuning speed.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EHeating Up Metasurfaces\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMetasurfaces are a class of nanophotonic materials in which a large range of miniaturized elements are engineered to affect the transmission and reflection of light at different frequencies in a controlled way.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026quot;When viewing under very strong microscopes, metasurfaces look like a periodic array of posts,\u0026rdquo; said Adibi. \u0026ldquo;The best analogy would be to think of a LEGO pattern formed by connecting many similar LEGO bricks next to each other.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESince their inception, metasurfaces have been used to demonstrate that very thin optical devices can affect light propagation with metalenses (the formation of thin lenses) being the most developed application.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDespite impressive progress, most demonstrated metasurfaces are passive, meaning their performance cannot be changed (or tuned) after fabrication. The work presented by Adibi and his team, led by Ph.D. candidate Sajjad Abdollahramezani, applies electrical heat to a special class of nanophotonic materials to create a platform that can enable reconfigurable metasurfaces to be easily manufactured with high levels of optical modulation.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EPCMs Provide the Answer\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EA wide range of materials may be used to form metasurfaces including metals, oxides, and semiconductors, but Abdollahramezani and Adibi\u0026rsquo;s research focuses on phase-change materials (PCMs) because they can form the most effective structures with the smallest feature sizes. PCMs are substances that absorb and release heat during the process of heating and cooling. They are called \u0026ldquo;phase-change\u0026rdquo; materials because they go from one crystallization state to another during the thermal cycling process. Water changing from a liquid to a solid or gas is the most common example.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe Georgia Tech team\u0026rsquo;s experiments are substantially more complicated than heating and freezing water. Knowing that the optical properties of PCMs can be altered by local heating, they have harnessed the full potential of the PCM alloy Ge\u003Csub\u003E2\u003C\/sub\u003ESb\u003Csub\u003E2\u003C\/sub\u003ETe\u003Csub\u003E5\u003C\/sub\u003E\u0026nbsp;(GST), which is a compound of\u0026nbsp;germanium,\u0026nbsp;antimony, and\u0026nbsp;tellurium.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EBy combining the optical design with a miniaturized electrical microheater underneath, the team can change the crystalline phase of the GST to make active tuning of the metasurface device possible.\u0026nbsp;The fabricated metasurfaces were developed at Georgia Tech\u0026rsquo;s\u0026nbsp;\u003Ca href=\u0022https:\/\/research.gatech.edu\/nano\u0022\u003EInstitute for Electronics and Nanotechnology\u003C\/a\u003E\u0026nbsp;(IEN) and tested in characterization labs by illuminating the reconfigurable metasurfaces with laser light at different frequencies and measuring the properties of the reflected light in real time.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EWhat Tunable Metasurfaces Mean for the Future\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDriven by device miniaturization and system integration, as well as their ability to selectively reflect different colors of light, metasurfaces are rapidly replacing bulky optical assemblies of the past. Immediate impact on technologies like LiDAR systems for autonomous cars,\u0026nbsp;imaging, spectroscopy, and sensing is expected.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWith further development, more aggressive applications like computing, augmented reality, photonic chips for artificial intelligence, and biohazard detection can also be envisioned, according to Abdollahramezani and Adibi.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;As the platform continues to develop, reconfigurable metasurfaces will be found everywhere,\u0026rdquo; said Adibi. \u0026ldquo;They will even empower smaller endoscopes to go deep inside the body for better imaging and help medical\u0026nbsp;sensors detect different biomarkers in blood.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECitation:\u003C\/strong\u003E\u0026nbsp;Abdollahramezani, S., Hemmatyar, O., Taghinejad, M.\u0026nbsp;et al.\u0026nbsp;Electrically driven reprogrammable phase-change metasurface reaching 80% efficiency.\u0026nbsp;Nat Commun13,\u0026nbsp;1696 (2022). https:\/\/doi.org\/10.1038\/s41467-022-29374-6\u003C\/p\u003E\r\n\r\n\u003Cdiv\u003E\r\n\u003Cp\u003E\u003Cstrong\u003EFunding:\u0026nbsp;\u003C\/strong\u003EThis material is based upon work supported by the National Science Foundation (NSF) under Grant No. 1837021. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. The work was primarily funded by Office of Naval Research (ONR) (N00014-18-1-2055, Dr. B. Bennett) and by Defense Advanced Research Projects Agency (D19AC00001, Dr. R. Chandrasekar). W.C. acknowledges support from ONR (N00014-17-1-2555) and National Science Foundation (NSF) (DMR-2004749). A. Al\u0026ugrave; acknowledges support from Air Force Office of Scientific Research and the Simons Foundation. M.W. acknowledges support by the Deutsche Forschungsgemeinschaft (SFB 917). M.E.S. acknowledges financial support of NSF-CHE (1608801). This work was performed in part at the Georgia Tech Institute for Electronics and Nanotechnology (IEN), a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by NSF (ECCS1542174).\u003C\/p\u003E\r\n\u003C\/div\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Harnessing the power of \u201cphase-change\u201d materials, Georgia Tech researchers have demonstrated how reconfigurable metasurfaces \u2014 artificial materials with extraordinary optical properties \u2014 are crucial to the future of nanotechnology.  "}],"uid":"36172","created_gmt":"2022-05-10 17:55:54","changed_gmt":"2022-05-13 21:02:11","author":"dwatson71","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2022-05-10T00:00:00-04:00","iso_date":"2022-05-10T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"658153":{"id":"658153","type":"image","title":"Ali Adibi and Sajjad Abdollahramezani","body":null,"created":"1652369892","gmt_created":"2022-05-12 15:38:12","changed":"1652374741","gmt_changed":"2022-05-12 16:59:01","alt":"ECE professor Ali Adibi with Ph.D. candidate Sajjad Abdollahramezani holding their packaged tunable metasurface device.","file":{"fid":"249489","name":"DSC01455.jpg","image_path":"\/sites\/default\/files\/images\/DSC01455.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/DSC01455.jpg","mime":"image\/jpeg","size":834176,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/DSC01455.jpg?itok=U_0m229J"}},"658071":{"id":"658071","type":"image","title":"Reconfigurable metasurfaces images graphic","body":null,"created":"1652204833","gmt_created":"2022-05-10 17:47:13","changed":"1652204833","gmt_changed":"2022-05-10 17:47:13","alt":"(I) Image of the fabricated sample mounted on a ceramic chip carrier, (II) tilted false-colored SEM image of the meta-switch comprising the microheater and the phase-change metasurface, and (III) the magnified bird\u2019s eye view of the meta-atom array. (IV) Tilted false-colored SEM image of the meta-switch comprising the microheater and the phase-change metasurface at 50 \u03bcm.","file":{"fid":"249451","name":"Reconfiguraly metasurfaces images graphic.jpg","image_path":"\/sites\/default\/files\/images\/Reconfiguraly%20metasurfaces%20images%20graphic.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/Reconfiguraly%20metasurfaces%20images%20graphic.jpg","mime":"image\/jpeg","size":1639843,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Reconfiguraly%20metasurfaces%20images%20graphic.jpg?itok=bxariuTL"}},"658154":{"id":"658154","type":"image","title":"Ali Adibi and Sajjad Abdollahramezani in lab","body":null,"created":"1652369990","gmt_created":"2022-05-12 15:39:50","changed":"1652374700","gmt_changed":"2022-05-12 16:58:20","alt":"ECE professor Ali Adibi with Ph.D. candidate Sajjad Abdollahramezani in Ali\u2019s Photonics Research Group lab where the characterization of the tunable metasurfaces takes place.","file":{"fid":"249488","name":"DSC01423.jpg","image_path":"\/sites\/default\/files\/images\/DSC01423.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/DSC01423.jpg","mime":"image\/jpeg","size":951114,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/DSC01423.jpg?itok=lxWui58e"}}},"media_ids":["658153","658071","658154"],"related_links":[{"url":"https:\/\/www.ece.gatech.edu\/faculty-staff-directory\/ali-adibi","title":"Ali Adibi "},{"url":"https:\/\/www.ece.gatech.edu","title":"ECE"},{"url":"https:\/\/sites.gatech.edu\/ece-prg\/people\/adibi\/","title":"Photonics Research Group "}],"groups":[{"id":"1255","name":"School of Electrical and Computer Engineering"},{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"129","name":"Institute and Campus"},{"id":"134","name":"Student and Faculty"},{"id":"8862","name":"Student Research"},{"id":"135","name":"Research"},{"id":"145","name":"Engineering"},{"id":"149","name":"Nanotechnology and Nanoscience"}],"keywords":[{"id":"190574","name":"Reconfigurable metasurfaces"},{"id":"190575","name":"Tunable metasurfaces"},{"id":"190576","name":"phase-change materials"},{"id":"2769","name":"Ali Adibi"},{"id":"220","name":"professor"},{"id":"188070","name":"Sajjad Abdollahramezani"},{"id":"2435","name":"ECE"},{"id":"187915","name":"go-researchnews"}],"core_research_areas":[{"id":"39451","name":"Electronics and Nanotechnology"},{"id":"39471","name":"Materials"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EDan Watson\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Ca href=\u0022http:\/\/dwatson@ece.gatech.edu\u0022\u003Edwatson@ece.gatech.edu\u003C\/a\u003E\u003C\/p\u003E\r\n","format":"limited_html"}],"email":["dwatson@ece.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}