Parametric Bragg resonances in waves on a shallow fluid over a periodically drilled bottom

Bragg resonances involving strong interactions among Fourier wave components of a periodically drilled bottom and parametrically driven surface waves on a shallow liquid are experimentally shown to break down the secular dispersion relation of surface waves. When the fluid is sufficiently shallow, wave components that match reciprocal wave vectors of the bottom topography are dominant. Experimental evidence of band-gap phenomena in these surface waves are also shown. Moreover, the prevalence of Bragg resonances is so strong that one of them is excited anomalously within the band gap.