Underwater Wireless Optical Communication based on Flexible CIGS Solar Cells

Solar cells have been employed in underwater wireless optical communication (UWOC) for data reception, featuring cost-effectiveness and easy optical alignment. However, crystalline silicon (c-Si) solar cells are rigid and impractical for deployment on curved or irregular surfaces. This letter presents a novel UWOC system that utilizes a flexible copper indium gallium selenide (CIGS) solar cell as the receiver, demonstrating potential for conformal integration onto the surface of submerged devices. The key challenge for practical implementation is preventing CIGS breakdown under reverse bias (required for bandwidth enhancement). Experiments show that at a reverse bias voltage of 14.7 V and a received optical power (ROP) of 12.67 dBm after a 7-m underwater transmission, the CIGS solar cell achieved the maximum data rates of 32 and 25 Mbit/s for flat and bent PV surface, respectively. Moreover, the flexible CIGS solar cell can still work at an ROP of -4 dBm, achieving a 6-Mbit/s data rate with the bit error rate (BER) under the forward error correction (FEC) limit. To the best of our knowledge, this work represents the first application of a flexible CIGS solar cell in a UWOC system. Their remarkable flexibility and cut-to-size capability highlight their potential for diverse UWOC applications.