Adaptive water-air-water data information transfer using orbital angular momentum.

With the increasing demands for underwater monitoring and military applications, underwater wireless optical communication (UWOC) is desired to be an alternative approach to provide higher data rate than acoustic communication. Twisted light carrying orbital angular momentum (OAM) has recently gained increasing interest in diverse areas, especially in free-space and fiber-based optical communications. OAM-based UWOC between underwater and aerial users, a promising technique to enable a variety of applications, which however, has not yet been reported so far. Here we experimentally demonstrate an adaptive water-air-water data information transfer using OAM. According to the feedback information of the received intensity distribution, the reflection element is adjusted for mitigating the misalignment-induced degradation effect due to water level change. The experimental results show favorable performance of the feedback-assisted water-air-water twisted light data information transfer.