Terahertz-wave generation from surface phonons at forbidden frequencies of lithium niobate

Jun Ichi Shikata, Seigo Ohno, Hiroaki Minamide

Research output: Contribution to journalArticlepeer-review


This paper describes terahertz (THz)-wave generation within forbidden bands in polar crystals, focusing on the A1 phonon modes in lithium niobate. This material exhibits two negative-permittivity frequency ranges at 7.4-12.7 THz and 18.8-25.6 THz for the lowest and highest A1 modes, respectively. Exploiting the finite-difference time-domain simulations, we demonstrate that both the surface phonon modes can be radiative with a structured grating. Fourier analyses of the radiative fields reveal the relevant peaks in the spectrum as well as the dispersion relations. Our results provide a novel method for coherent THz-wave sources at unexplored THz frequencies.

Original languageEnglish
JournalIEICE Electronics Express
Issue number11
Publication statusPublished - 2020


  • A mode
  • Lithium niobate
  • Negative permittivity
  • Surface phonon
  • Terahertz-wave generation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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