Propagation-Invariant Space–Time Plasmonic Pulse in Subwavelength MIM Waveguide

Eui Soo Cho, Seung Yeol Lee

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number425
Issue number5
StatePublished - Mar 2024


  • diffraction-free beams
  • metal-insulator-metal plasmonic waveguide
  • propagation-invariant wave packets
  • space–time wave packets
  • surface plasmon polaritons


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