Condensed Matter Seminar: Control of coherent phenomena in complex photonic media

Abstract:

Multiple scattering of light leads to universal coherent phenomena that are surprisingly robust to ensemble averaging. A prominent example is coherent backscattering, where time-reversed paths inside a complex disordered sample interfere constructively and enhance the backscattered light. The constructive interference is insensitive to averaging over disorder realizations, by virtue of the optical reciprocity principle. An open question is whether it is possible to take advantage of such coherent phenomena to control the light transport in a robust manner, which does not depend on the exact configuration of the disordered sample.  In my talk I will present our recent work towards this end. We demonstrated a control over the interference of time-reversed paths inside a multimode fiber with strong mode mixing. By exploiting a non-reciprocal magneto-optical effect, we were able to observe a continuous transition from a peak to a dip in the backscattered light, where the transition was insensitive to the configuration of the fiber. I will also show how we can utilize the strong mode mixing in multimode fibers and the robust interference of time-reversed paths, for secure optical communication.

Seminar Organizer: Prof. Shimshon Barad