Cho Eui-Soo, Lee Seung-Yeol
School of Electronic and Electrical Engineering, College of IT Engineering, Kyungpook National University, Daegu 41566, Republic of Korea.
Nanomaterials (Basel). 2024 Feb 26;14(5):425. doi: 10.3390/nano14050425.
The metal-insulator-metal (MIM) plasmonic waveguide has been highly anticipated for confining and guiding surface plasmon polaritons (SPPs) on the subwavelength scale. However, perennial drawbacks such as a short propagation length and an unbounded transverse field have set limits on the use of the MIM waveguide in various applications. Herein, diffraction- and dispersion-free MIM modes are synthesized by using space-time wave packets (STWPs) and are therefore referred to as space-time MIM (ST-MIM) waveguide modes. Compared to a Gaussian pulse of the same duration and spectral bandwidth, the ST-MIM demonstrates enhanced propagation lengths of about 2.4 times for the symmetric mode and about 6.3 times for the antisymmetric mode. In the simulations, the ST-MIMs are confined in all transverse dimensions, thereby overriding the diffraction limits. In addition, the group velocities of the ST-MIMs can be arbitrarily designed, which makes it possible to synchronize the pulse propagation speeds of the symmetric and antisymmetric MIM modes.
金属-绝缘体-金属（MIM）等离子体波导一直备受期待，有望在亚波长尺度上限制和引导表面等离激元极化激元（SPP）。然而，诸如传播长度短和横向场无界等长期存在的缺点限制了MIM波导在各种应用中的使用。在此，通过使用时空波包（STWP）合成了无衍射和无色散的MIM模式，因此被称为时空MIM（ST-MIM）波导模式。与具有相同持续时间和光谱带宽的高斯脉冲相比，ST-MIM的对称模式传播长度增强了约2.4倍，反对称模式增强了约6.3倍。在模拟中，ST-MIM在所有横向维度上都受到限制，从而突破了衍射极限。此外，ST-MIM的群速度可以任意设计，这使得对称和反对称MIM模式的脉冲传播速度同步成为可能。
