###### Abstract  
Underwater wireless optical communication (UWOC) has attracted increasing attention due to its advantages in bandwidth, latency, interference resistance, and security. Photodetectors, as a crucial part of receivers, have been continuously developed with the great progress that has been made in advanced materials. Metal halide perovskites emerging as promising optoelectronic materials in the past decade have been used to fabricate various high-performance photodetectors. In this work, high-performance CsPbBr3 perovskite PDs were realized via solution process, with low noise, a high responsivity, and a fast response. Based on these perovskite PDs, a cost-efficient UWOC system was successfully demonstrated on an FPGA platform, achieving a data rate of 6.25 Mbps with a low bit error rate of 0.36%. Due to lower background noise under environment illumination, perovskite PDs exhibit better communication stability before reaching a data rate threshold; however, the BER increases rapidly due to the long fall time, resulting in difficulty in distinguishing switching signals. Reducing the fall time of perovskite PDs and using advanced coding techniques can help to further improve the performance of the UWOC system based on perovskite PDs. This work not only demonstrates the potential of perovskite PDs in the application of UWOC, but also improves the development of a cost-effective UWOC system based on FPGAs. perovskite; photodetector; underwater wireless optical communication; visible light communication; CsPbBr3 2024 15 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 11185 1185 1185 1185 1185 1185 1185 1185 1185 1185 1185 11185 11185 11 Recently, much effort has been made to improve the performance of UWOC regarding light sources and modulation in transmitting end [8; 9], the influence of water [10; 11], photodetectorsin the receiver [12; 13], multiple-input multiple-output configurations [14], and signal processing [15; 16]. Field-programmable gate arrays (FPGAs) have become crucial hardware platforms in modern communication systems, due to their flexibility and efficiency. The programmability of FPGAs allows designers to dynamically configure hardware functions for quickly adapting to different communication protocols and standards. In visible light communication systems, the parallel processing capabilities of FPGA favor high-precision ADC data transmission, providing effective data processing without custom integrated circuits [17; 18]. Several groups have demonstrated UWOC systems using FPGAs [18; 19; 20]. [PERSON] et al. from the Computer Science and Artificial Intelligence Laboratory have demonstrated a UWOC system based on FPGAs, and achieved a data rate of 1.2 Mbps at distances of up to 30 m in clear water [21]. Later, they achieved a real-time video delivery with 15 frames per second of 1288 \(\times\) 964-pixel images based on the updated UWOC system with a 4 Mbps bandwidth [22]. [PERSON] et al. achieved a data rate of at least 50 Mbps with a very low bit error rate (BER) over an underwater channel of 1 m [19]. Even though the data rate is far lower than that of offline systems at the gigabit level [23; 24], UWOC systems based on FPGA boards, without using expensive and complicated equipment, show huge potential in their light weight and low cost, and this is also a critical step for achieving real-time communication [20]. Sea water as a communication medium has a low-loss window in the blue-green light spectrum (450 nm-550 nm) [25], in which an optical signal has a minimum attenuation and the largest transmission distance. All inorganic CsPbBr\({}_{3}\) perovskite possessing outstanding optoelectronic properties (high absorption coefficient, high carrier mobility, etc.) [26] are promising candidates for optical receivers in UWOC systems.