Characterization of the femtosecond speckle field of a multiply scattering medium via spatio-spectral interferometry
Résumé
Propagation of an ultrashort laser pulse through a scattering medium forms a speckle pattern in the spatio-spectral domain. This pattern arises from the contribution of the randomly phased electric fields associated with the different optical paths in the medium. Studying the speckle field provides information both about the diffusion properties of the medium and spatio-temporal control of the transmitted or scattered light. In this paper a spatio-temporal characterization of the near-IR 120 fs pulse transmitted through a thick strongly scattering medium is undertaken using spatially and spectrally resolved Fourier-transform interferometry (SSI). The advantages of SSI over conventional pulse measurement techniques are discussed. The diffusion properties of the scattering samples are measured. We find a good agreement between our measured diffusion properties and those obtained using another method. The implications of this measurement technique are discussed.