Shaping Green’s Functions in Cavities with Tunable Boundary Conditions: From Fundamental Science to Applications
Speaker: Philipp del Hougne, ESPCI, Institut Langevin, Paris
Title: Shaping Green’s Functions in Cavities with Tunable Boundary Conditions: From Fundamental Science to Applications
Abstract: For a long time, the complete scrambling of a wavefront as it propagates through a complex (random) medium was considered absolutely detrimental to information transfer. A complex medium consists of many scatterers or reflectors that act as random secondary sources, yielding speckle-like output wave fields. More recently, various techniques emerged that embrace these secondary sources as degrees of freedom, notably Time Reversal in Acoustics and Wavefront Shaping in Optics. In this talk, I will discuss how the idea of wavefront shaping in complex media can be transposed to the microwave domain. A common complex medium for microwaves is the disordered cavity, with examples ranging from indoor wireless communication, via electromagnetic compatibility tests to computational imaging. I will show how simple tunable reflect-arrays partially covering the cavity’s walls can pave the path towards dynamically shaping the field inside a cavity of fixed geometry and discuss the underlying Physics. Then, I will present an example of how this concept enables the conception of a localization sensor for context-aware Smart Buildings. Finally, I will discuss if ubiquitous Wi-Fi waves could be tamed such that they perform analogue computation simply by reverberating in a room.