23 Gbit/s underwater wireless optical communications using directly modulated 520 nm laser diode

TLDR

We experimentally demonstrate record‑high‑speed underwater wireless optical communication over 7 m using OOK‑NRZ modulation. The system employs a 520 nm laser diode with 1.2 GHz bandwidth and an APD receiver, whose high bandwidth and sensitivity, together with optimized operating conditions, enable the high‑rate transmission. We achieved 2.3 Gbit/s over 7 m with a BER of 2.23×10⁻⁴, below the FEC threshold, marking the highest data rate reported for UWOC to date.

Abstract

We experimentally demonstrate a record high-speed underwater wireless optical communication (UWOC) over 7 m distance using on-off keying non-return-to-zero (OOK-NRZ) modulation scheme. The communication link uses a commercial TO-9 packaged pigtailed 520 nm laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter and an avalanche photodiode (APD) module as the receiver. At 2.3 Gbit/s transmission, the measured bit error rate of the received data is 2.23×10(-4), well below the forward error correction (FEC) threshold of 2×10(-3) required for error-free operation. The high bandwidth of the LD coupled with high sensitivity APD and optimized operating conditions is the key enabling factor in obtaining high bit rate transmission in our proposed system. To the best of our knowledge, this result presents the highest data rate ever achieved in UWOC systems thus far.