Multi-gigabit/s underwater optical communication link using orbital angular momentum multiplexing

In this work we experimentally demonstrated an underwater wireless optical communications (UWOC) link over a 2.96 m distance with two 445-nm fiber-pigtailed laser diodes employing Orbital Angular Momentum (OAM) to allow for spatial multiplexing. Using an on-off keying, non-return-to-zero (OOK-NRZ) modulation scheme, a data rate of 3 Gbit/s was achieved in water with an attenuation coefficient of 0.4128 m^-1 at an average bit error rate (BER) of 2.073 × 10^-4, well beneath the forward error correction (FEC) threshold.