  Recent years have heralded the introduction of metasurfaces that
advantageously combine the vision of sub- wavelength wave manipulation, with
the design, fabrication and size advantages associated with surface excitation.
An important topic within metasurfaces is the tailored rainbow trapping and
selective spatial frequency separation of electromagnetic and acoustic waves
using graded metasurfaces. This frequency dependent trapping and spatial
frequency segregation has implications for energy concentrators and associated
energy harvesting, sensing and wave filtering techniques. Different
demonstrations of acoustic and electromagnetic rainbow devices have been
performed, however not for deep elastic substrates that support both shear and
compressional waves, together with surface Rayleigh waves; these allow not only
for Rayleigh wave rainbow effects to exist but also for mode conversion from
surface into bulk waves. We design, and test experimentally, a device creating
not only elastic Rayleigh wave rainbow trapping, but also selective mode
conversion of surface Rayleigh waves to shear waves.
