Roh, Yeeun Chae, Minjun Oh, Jaewon Kim, Woochul Ryu, Mee-Yi Seo, Minah Jeong, Jeeyoon 2024-01-19T09:02:32Z 2024-01-19T09:02:32Z 2023-08-11 2023-08 1530-6984 https://pubs.kist.re.kr/handle/201004/113430 Metallic nanogaps have emerged as a versatile platformfor realizingultrastrong coupling in terahertz frequencies. Increasing the couplingstrength generally involved reducing the gap width to minimize themode volume, which presents challenges in fabrication and efficientmaterial coupling. Here, we propose employing terahertz nanoslots,which can efficiently squeeze the mode volume in an extra dimensionalongside the gap width. Our experiments using 500 nm wide nanoslotsintegrated with an organic-inorganic hybrid perovskite demonstrateultrastrong phonon-photon coupling with a record-high Rabisplitting of 48% of the original resonance (& omega; = 0.48 & omega;(0)), despite having a gap width 5 times larger than previouslyreported structures with & omega; = 0.45 & omega;(0). Mechanismsunderlying this effective light--matter coupling are investigatedwith simulations using coupled mode theory. Moreover, bulk polaritonanalyses reveal that our results account for 68% of the theoreticalmaximum Rabi splitting, with the potential to reach 82% through furtheroptimization of the nanoslots. English American Chemical Society Ultrastrong Coupling Enhancement with Squeezed Mode Volume in Terahertz Nanoslots Article 10.1021/acs.nanolett.3c01913 1 Nano Letters, v.23, no.15, pp.7086 - 7091 Nano Letters 23 15 7086 7091 N scie scopus 001033069500001 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article ultrastrong coupling perovskites terahertz phonon-polariton nanoslots