Green's Function Retrieval with Absorbing Probes in Reverberating Cavities

Matthieu Davy (1) , Julien de Rosny (2) , Philippe Besnier (1)

1 IETR - Institut d'Électronique et des Technologies du numéRique
2 IL - Institut Langevin - Ondes et Images (UMR7587)

The cross-correlation of a diffuse wave field converges toward the difference between the anticausal and causal Green's functions between two points. This property has paved the way to passive imaging using ambient noise sources. In this Letter, we investigate Green's function retrieval in electromagnetism. Using a model based on the fluctuation dissipation theorem, we demonstrate theoretically that the cross-correlation function strongly depends on the absorption properties of the receivers. This is confirmed in measurements within a reverberation chamber. In contrast to measurements with noninvasive probes, we show that only the anticausal Green's function can be retrieved with a matched antenna. Finally, we interpret this result as an equivalent time-reversal experiment with an electromagnetic sink.

Keywords: noise cross-correlation; ambient noise; diffuse field; light; fluctuations; localization; emergence; thevenin; sensors; waves

Domains: Engineering Sciences [physics]; Electronics

Matthieu Davy, Julien de Rosny, Philippe Besnier. Green's Function Retrieval with Absorbing Probes in Reverberating Cavities. Physical Review Letters, 2016, 116 (21), pp.213902. ⟨10.1103/PhysRevLett.116.213902⟩. ⟨hal-01343529⟩