Imaging localized phononic cavity modes with laser interferometer

In this work, we experimentally confirmed an effective Lamb-wave guiding method, which utilizes a localized phononic cavity mode in a 2D phononic crystal. The phononic crystal is created by a periodic distribution of solid pillars built on an elastic plate, while the cavity mode is induced by replacing part of the pillars by the hollow pillars. In the experiments, transmission characteristics of the Lamb-waves within the waveguides are studied comprehensively. Elastic field distributions of the cavity mode are mapped in the deep-subwavelength regime. In geometrical shapes, both a straight waveguide and a bended one are made for practical measurement, demonstrating visually that the elastic energies are well localized around the hollow pillars and can be transported around the bends.