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 dB 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.

中文翻译：

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水下光子互相关光通信

大容量、长距离的水下光通信使覆盖轨道、陆地和水域的全球尺度光网络成为可能。以光子为载体的水下通信信道容量高；然而，水的光散射和吸收导致不可避免的巨大信道损耗，为现有的水下光通信技术设置了无法逾越的传输距离。在这里，我们通过实验证明了空气-水场景中的光子互相关光通信（PICOC）。我们以高保真度从稀疏的单光子流中检索额外的内部相关资源。我们仅使用微瓦激光器就成功实现了 105 米长的水下光通信，总损耗高达 120.1 dB。