Kang, Taehee Kim, Richard H. J. Lee, Jinwoo Seo, Minah Kim, Dai-Sik 2024-01-19T08:04:47Z 2024-01-19T08:04:47Z 2023-11-29 2024-04 2192-8606 https://pubs.kist.re.kr/handle/201004/113115 Probing the time evolution of the terahertz electric field within subwavelength dimensions plays a crucial role in observing the nanoscale lightwave interactions with fundamental excitations in condensed-matter systems and in artificial structures, such as metamaterials. Here, we propose a novel probing method for measuring terahertz electric potentials across nanogaps using a combination of optical and terahertz pulse excitations. To achieve this, we employ ring-shaped nanogaps that enclose a metallic island, allowing us to capture tunneling charges when subjected to terahertz electromagnetic pulse illumination. By controlling and manipulating the terahertz tunneling charges through a focused optical gate pulse, we can obtain the terahertz potential strength as a function of spatial coordinates and time delays between pulses. To accurately quantify the time evolution of terahertz electric potential across quantum barriers, we carefully calibrate the recorded nonlinear tunneling current. Its on-resonance and off-resonance behaviors are also discussed, providing valuable insights into the antenna's characteristics and performance. English WALTER DE GRUYTER GMBH Ultrafast snapshots of terahertz electric potentials across ring-shaped quantum barriers Article 10.1515/nanoph-2023-0538 1 Nanophotonics, v.13, no.8, pp.1331 - 1338 Nanophotonics 13 8 1331 1338 Y scie scopus 001096857800001 2-s2.0-85176006628 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Optics Physics, Applied Science & Technology - Other Topics Materials Science Optics Physics Article FIELD ENHANCEMENT NEAR-FIELD SPECTROSCOPY light-field-driven electron tunneling metal-insulator-metal structures nano resonators terahertz electric potential mapping terahertz imaging ultrafast imaging