Grant: Discovery Grants Program - Individual

Waves in complex media exhibit remarkable properties, many of which result from strong multiple scattering and which continue to challenge our basic understanding of wave physics. This subject underpins many scientific and engineering disciplines that rely on wave-based techniques for imaging and materials characterization. The transport of waves through complex media is also fundamental to our prosperity, as it affects, for example, our ability to image complex structures (e.g., defects in concrete bridges and technological devices) and to effectively prospect for and extract natural resources. The goals of my research program are to build on recent progress in my laboratory to address the most important unresolved questions in the wave physics of complex strongly scattering materials, and to develop and use new techniques, based on our knowledge of wave scattering, to probe their structure and dynamics. To achieve these objectives, my students and I will perform state-of-the-art ultrasonic experiments, using techniques that we have pioneered and that are recognized internationally as some of the most powerful approaches to addressing many key challenges in the field. Our unique advantage stems from our ability to record complete information about wave transport, the feasibility of studying materials with precisely determined structures, the convenient range of lengths and times involved, and the possibility of interpreting our data using new theoretical models. Examples of intriguing wave phenomena that we will investigate include Anderson localization (the ultimate trapping of waves due to disorder) and the remarkable focusing properties of artificially structured materials (phononic crystals and metamaterials) due to negative refraction. We will also develop new dynamic imaging methods for complex media (in which traditional imaging techniques fail), leading to new ultrasonic spectroscopies for materials characterization and process control. We will use these techniques to study porous and granular materials, foams, bubbly gels, and aerated food biomaterials. The universality of wave behaviours implies that the impact of our research may extend well beyond ultrasonics, facilitating advances in other fields of research.