Pulse Dynamics of Flexural Waves in Transformed Plates

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, is likely to deteriorate for short pulses. Here, pulse dynamics of flexural waves propagating in transformed plates is investigated. A practical realization of a waveshifter and a rotator for flexural waves based on the coordinate transformation method is proposed. 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 the strategy to cylindrical coordinates, a wave rotator is designed. It is demonstrated 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. The realization of the dynamical mirage effect is proposed, where an obstacle appears oriented in a deceptive direction.

Automated summary

Coordinate-transformation-inspired optical devices, such as wave shifters and rotators, have been proposed for flexural waves based on the coordinate transformation method. Experimental results show that the wave shifter can deviate a short pulse without reflection or temporal distortion. Additionally, a wave rotator designed in cylindrical coordinates is demonstrated to twist a pulsed plane wave while maintaining wavefront integrity and pulse shape, without introducing extra time delay.