Guidance of surface waves in a micron-scale phononic crystal line-defect waveguide

We report on the direct observation of trapping and guiding of surface-guided elastic waves in a linear defect introduced into a micron-scale phononic crystal. Elastic field amplitude detection using laser scanning interferometry was used to characterize the different transmission regimes of the one-period wide line defect in a phononic crystal structure as a function of frequency and to discriminate phononic waveguiding from transmission outside the band gap. Surface density-of-states computations support the experimental observations.