Kang Taehee, Kim Richard H J, Lee Jinwoo, Seo Minah, Kim Dai-Sik
Sensor System Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.
Ames National Laboratory, Ames, IA 50011, USA.
Nanophotonics. 2023 Nov 2;13(8):1331-1338. doi: 10.1515/nanoph-2023-0538. eCollection 2024 Apr.
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.
在亚波长尺度内探测太赫兹电场的时间演化，对于观察凝聚态物质系统以及人工结构（如超材料）中纳米级光波与基本激发之间的相互作用起着至关重要的作用。在此，我们提出一种新颖的探测方法，利用光学和太赫兹脉冲激发相结合的方式来测量纳米间隙上的太赫兹电势。为实现这一点，我们采用环绕金属岛的环形纳米间隙，当受到太赫兹电磁脉冲照射时，这使我们能够捕获隧穿电荷。通过聚焦光学门脉冲控制和操纵太赫兹隧穿电荷，我们可以获得作为空间坐标和脉冲之间时间延迟函数的太赫兹电势强度。为了准确量化太赫兹电势在量子势垒上的时间演化，我们仔细校准记录的非线性隧穿电流。还讨论了其共振和非共振行为，为天线的特性和性能提供了有价值的见解。
