Retrieving time-dependent Green's functions in optics with low-coherence   interferometry
  We report on the passive measurement of time-dependent Green's functions in the optical frequency domain with low-coherence interferometry. Inspired by previous studies in acoustics and seismology, we show how the correlations of a broadband and incoherent wave-field can directly yield the Green's functions between scatterers of a complex medium. Both the ballistic and multiple scattering components of the Green's function are retrieved. This approach opens important perspectives for optical imaging and characterization in complex scattering media. 
Amaury Badon, Geoffroy Lerosey, Albert C. Boccara, Mathias Fink,   Alexandre Aubry
physics.optics cond-mat.dis-nn