Spatial coherence of light inside three-dimensional media

Abstract Speckle is maybe the most fundamental interference effect of light in disordered media, giving rise to fascinating physical phenomena and cutting edge applications. While speckle formed outside a sample easily measured analysed, true bulk speckle, as inside random difficult investigate directly due obvious issue access. Furthermore, its proper theoretical description poses enormous challenges. Here we report on first direct measurements spatially resolved intensity correlations medium, using embedded DNA strings decorated with emitters separated by controlled nanometric distance. Our method provides situ access properties speckles their size polarization degrees freedom, both which are found deviate significantly from predictions. The deviations explained, comparison rigorous numerical calculations, terms among components non-universal near-field contributions at nanoscale.