Time-Varying Phononic Crystals

Derek Wright

Recent alumni from U of T's collaborative electrical and biomedical engineering program

Abstract:

During the past few years there have been remarkable discoveries concerning negative refraction at optical and microwave frequencies using certain metamaterials, including photonic crystals. These have stimulated major interest in the development and nderstanding of their acoustic wave analogue, namely phononic crystals. Outcomes of this research have been new methods of ultrasound beam control and the achievement of super-resolution imaging similar to that already predicted and experimentally demonstrated for homogeneous metamaterials, and subsequently predicted for photonic crystals. This makes possible the creation of subwavelength resolution lenses, planar focusing, and even a Harry Potter invisibility cloak for acoustic waves.

Our research group has been investigating phononic crystals, in particular, their scattering and refractive properties. We have proposed a method of controlling these crystals by varying one or more of their design parameters as a function of time. We have also extended the existing analytical models of phononic crystals to include the effects of time-varying material parameters. These devices may one day lead to dynamic materials whose properties are tuneable in real-time, such as a solid-state ultrasonic lens with a variable focal length.

Biography:

Derek Wright received the B.A.Sc. degree in electrical engineering and the M.A.Sc. degree in electrical and computer engineering from the University of Waterloo, Canada, in 2003 and 2005, respectively, and the Ph.D. degree in the collaborative electrical and biomedical engineering program at the University of Toronto, Canada, in 2009. His research interests are in ultrasonic phononic crystals and metamaterials. In particular, he is investigating how phononic crystals that use dynamic materials, such as piezoelectrics and dielectric elastomers, may one day lead to controllable dynamic ultrasonic lenses. He currently works at Maplesoft.