Memory effects in propagation of optical waves through disordered media

We verify experimentally for optical waves the striking memory effect predicted very recently by Feng, Kane, Lee, and Stone. We present data for both transmission and reflection, and find general agreement with the theoretical predictions for the linear scale dependence and asymptotic exponential falloff of the memory effect. The theoretical and experimental results suggest that significant information about the spatial variation of the incident waveform is preserved during passage through a highly disordered, strongly multiply scattering medium.