Measurements on the optical transmission matrices of strongly scattering nanowire layers

Abstract

Summary form only given. Light incident on a scattering medium is redistributed over transport channels that either transmit through or reflect from the medium. We perform experiments aiming at finding individual transport channels of extremely strongly scattering materials. A small number of transport channels in a scattering sample are open with transmission coefficient close to 1; field transmission mainly takes place through these channels [1-3]. This means that, even if two very different incident fields are sent to the sample, the corresponding transmitted fields are correlated. As the scattering becomes stronger, these correlations become more pronounced.One way to investigate these correlations is to construct a transmission matrix by measuring the fields transmitted through the medium in response to pre-determined incident fields. Recently, microwave and optical experiments have been performed on measurements on the transmission matrices of scattering materials. In these studies, knowledge of the transmission matrix have been used for focusing [4, 5] and enhancing the transmission [6] through disordered media, or to study predictions of random matrix theory [7]. An observation of correlations in the optical transmission matrices of strongly scattering materials have not been reported so far. We measure transmission matrices of strongly scattering layers of disordered GaP nanowires, which are among the strongest scattering materials for visible light. The samples under study have thicknesses varying between -1.5 μm and -6 μm and transport mean free path of -0.2 μm [8]. We investigate the correlations in the measured transmission matrices and compare our experimental findings to a numerical model in order to retrieve physical parameters such as the scattering strength of the samples.