Replenishing the power supply system of an underwater communication system is usually very expensive and impractical. The underwater Simultaneous Light-wave Information and Power Transmission (SLIPT) communication systems based on solar cells are powerful solutions. However, the communication bandwidth of the silicon solar cell receiver is very limited, and it is easy to have the phenomenon of deep fading of the Signal-to-Noise Ratio (SNR) due to the underwater light attenuation effect.

For these problems, this manuscript employs a negative-biased solar cell light receiver scheme that increases the-3 dB bandwidth of silicon solar cells from 420 kHz to 768 kHz. Aiming at the deep fading of SNR caused by various degradation effects in the water environment, a Discrete Fourier Transfor (DFT) extended Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme with a low peak-average power ratio is adopted to offset the deep fading phenomenon in the system.

The performance of DFT Spread OFDM (DFT-S-OFDM) and OFDM modulation systems in water environments with different turbidity (absorption and scattering characteristics) is compared. It is shown that the DFT-S-OFDM modulation and demodulation system is more robust.

Finally, experiments have shown that the total battery power efficiency of the energy harvesting system can be increased by 1.87 times under continuous illumination of white LEDs for 3 h, realizing synchronized energy harvesting in the communication process.