Third-order nonlinear femtosecond optical gating through highly scattering media

Discriminating between ballistic and diffuse components of light propagating through highly scattering media is not only important for imaging purposes but also for investigating the fundamental diffusion properties of the medium itself. Massively developed to this end over the past 20 years, nonlinear temporal gating remains limited to ∼10-10 transmission factors. Here, we report nonlinear time-gated measurements of highly scattered femtosecond pulses with transmission factors as low as ≈10-12. Our approach is based on the third-order nonlinear cross-correlation of femtosecond pulses, a standard diagnostic used in high-power laser science, applied to the study of fundamental light scattering properties.