Underwater photon-inter-correlation optical communication

High-capacity,long-distance underwater optical communication enables a global scale optical network covering orbit,land,and water.Underwater communication using photons as carriers has a high channel capacity;however,the light scattering and absorption of water lead to an inevitable huge channel loss,setting an insurmountable transmission distance for existing underwater optical communication technologies.Here,we experimentally demonstrate the photon-inter-correlation optical communication(PICOC)in air-water scenarios.We retrieve additional internal correlation resources from the sparse single-photon stream with high fidelity.We successfully realize the 105-m-long underwater optical communication against a total loss up to 120.1 d B using only a microwatt laser.The demonstrated underwater light attenuation is equivalent to the loss of 883-m-long Jerlov type I water,encouraging the practical air-water optical communication to connect deeper underwater worlds.