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Non-reciprocal wave propagation in space-time modulated media

by H. Ammari and J. Cao and E.O. Hiltunen

(Report number 2021-27)

Abstract
We prove the possibility of achieving non-reciprocal wave propagation in space-time modulated media and give an asymptotic analysis of the non-reciprocity property in terms of the amplitude of the time-modulation. Such modulation causes a folding of the band structure of the material, which may induce degenerate points. By breaking time-reversal symmetry, we show that these degeneracies may open into non-symmetric, unidirectional band gaps. Finally, we illustrate our results by several numerical simulations.

Keywords: non-reciprocal wave propagation, unidirectional wave, subwavelength quasifrequency, time-modulation, space-time modulated medium, metamaterial, band gap structure

@Techreport{ACH21_969,
  author = {H. Ammari and J. Cao and E.O. Hiltunen},
  title = {Non-reciprocal wave propagation in space-time modulated media},
  institution = {Seminar for Applied Mathematics, ETH Z{\"u}rich},
  number = {2021-27},
  address = {Switzerland},
  url = {https://www.sam.math.ethz.ch/sam_reports/reports_final/reports2021/2021-27.pdf },
  year = {2021}
}

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