Fig. 4: Phase modulation of the unidirectionally-transmitted elastic meta-atoms (UTEM).
From: Unidirectional focusing for broadband Lamb guided wave based on mode conversion
a Dispersion curves for S0- (red solid line and circles) and A0-mode (blue short dashed line and triangles) Lamb waves on a 2 mm-thick aluminum plate. The shaded area indicates the operating frequency range. Inset: phase velocity difference between S0- and A0-mode Lamb waves. b Schematic diagram of a UTEM with the capability of broadband phase modulation. lS denotes for the propagation length of S0-mode Lamb wave. c Transmission phases and d amplitudes as a function of lS. The legend of d refers to (c).
