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 about 10e-10 transmission factors. Here, we report nonlinear time gated measurements of highly scattered femtosecond pulses with transmission factors as low as 10e-12. Our approach is based on third-order nonlinear cross-correlation of femtosecond pulses, a standard diagnostic used in high-power laser science, applied for the first time to the study of fundamental light scattering properties.