Photonics beyond multiple light scattering

Multiple light scattering occurring in a scattering medium undermines imaging targets embedded in the medium and attenuates the intensity of propagating waves. In this talk, I will introduce an experimental method that makes use of multiple-scattered waves for performing optical imaging and enhancing light energy delivery through scattering media. Specifically, we measured a transmission matrix of a scattering medium and used it to convert the medium as a unique lens. An example includes an endoscopic imaging by a single strand of multimode fiber, a special case of the scattering media. We also coupled light to the so-called eigenchannels of the medium identified from the measured matrix, some of which have extraordinary transmittance. I will conclude my talk by introducing a new deep-tissue imaging method that maintains full optical resolution in imaging deep within scattering media. We used both a time-gated detection and a spatial input-output correlation to identify those reflected waves that conserve in-plane momentum, which is the property of the single-scattered waves. Imaging depth of 11.5 times the scattering mean free path was achieved with near-diffraction-limit resolution of 1.5 μm. These studies altogether will lead to great important applications in deep-tissue optical bio-imaging and disease treatment.