High-order homogenisation of the time-modulated wave equation:\n non-reciprocity for a single varying parameter Article Swipe
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· 2023
· Open Access
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· DOI: https://doi.org/10.48550/arxiv.2311.10096
· OA: W4388843109
Laminated media with material properties modulated in space and time in the\nform of travelling waves have long been known to exhibit non-reciprocity.\nHowever, when using the method of low frequency homogenisation, it was so far\nonly possible to obtain non-reciprocal effective media when both material\nproperties are modulated in time, in the form of a Willis-coupling (or\nbi-anisotropy in electromagnetism) model. If only one of the two properties is\nmodulated in time, while the other is kept constant, it was thought impossible\nfor the method of homogenisation to recover the expected non-reciprocity since\nthis Willis-coupling coefficient then vanishes. Contrary to this belief, we\nshow that effective media with a single time-modulated parameter are\nnon-reciprocal, provided homogenization is pushed to the second order. This is\nillustrated by numerical experiments (dispersion diagrams and time-domain\nsimulations) for a bilayered modulated medium.\n
