Colloquium: Prof. John Page
Prof. John H. Page
Department of Physics
University of Manitoba
Friday Oct 3, 4:00–5:00pm, 211 Witmer Hall. Refreshments at 3:30pm.
Waves in Complex Media: from super-resolution focusing in phononic crystals
to Anderson localization in three-dimensional "mesoglasses"
Waves in complex media are often strongly scattered due to mesoscopic heterogeneities, leading to unusual and fascinating phenomena which continue to challenge our basic understanding of wave physics. Examples range from strikingly large variations in wave speeds to unusual refraction and tunneling effects, and even to the complete inhibition of wave propagation, due to disorder, that may occur in very strongly scattering samples when waves become localized. Ultrasonic techniques are well suited for investigating such phenomena since complete information about wave propagation (both amplitude and phase, in both time and space) can be measured directly in samples with well controlled internal structures. After an introduction to some of the general features of ultrasonic wave transport in both ordered and disordered mesoscopic materials (e.g., phononic crystals and "mesoglasses"), I will focus on our recent progress in answering the long–standing question of whether or not the Anderson localization of classical waves can really occur in three-dimensional disordered materials. This work is making it possible to study aspects of classical wave localization that have not previously been amenable to experimental investigation, and is contributing to the current resurgence of interest in localization across several domains of physics.