Ultrasonic Wedges for Elastic Wave Bending and Splitting without Requiring a Full Band Gap

We present a novel twinned-square periodic structure for ultrasonic wave bending and splitting that does not require the existence of a complete band gap and plays the role of an ultrasonic wedge. The device allows 45° bending of waves and by adequately switching the twinned structure to an ultrasonic crystal 90° bending is achieved. An extreme refraction law at the grain boundaries is experimentally observed.