Pulse dynamics of flexural waves in transformed plates

TL;DR

This paper explores the behavior of flexural waves in transformed plates, demonstrating devices like a waveshifter and rotator that manipulate pulse trajectories without distortion, advancing wave control in elastic media.

Contribution

It introduces practical designs for flexural wave devices based on coordinate transformation, with experimental validation showing preserved pulse shape and no reflections.

Findings

Waveshifter deviates pulses without reflection or distortion.

Rotator twists pulses while preserving wavefront and shape.

Proposes a dynamical mirage effect for elastic waves.

Abstract

Coordinate-transformation-inspired optical devices have been mostly examined in the continuous-wave regime: the performance of an invisibility cloak, which has been demonstrated for monochromatic excitation, %would inevitably is likely to deteriorate for short pulses. Here we investigate pulse dynamics of flexural waves propagating in transformed plates. We propose a practical realization of a waveshifter and a rotator for flexural waves based on the coordinate transformation method. Time-resolved measurements reveal how the waveshifter deviates a short pulse from its initial trajectory, with no reflection at the bend and no spatial and temporal distortion of the pulse. Extending our strategy to cylindrical coordinates, we design a wave rotator. We demonstrate experimentally how a pulsed plane wave is twisted inside the rotator, while its wavefront is recovered behind the rotator and the pulse shape is preserved, with no extra time delay. We propose the realization of the dynamical mirage effect, where an obstacle appears oriented in a deceptive direction.