Ince-Gaussian (IG) beams are widely used in the fields of beam generation and application due to their unique beam structure and phase distribution. In free-space optical communication, especially in atmospheric turbulent channels, IG beams show better anti-interference ability than Gaussian beams. However, the ocean turbulent channel environment is more complex and changeable, and the impact on the beams is more serious. To study the beam and signal transmission and communication characteristics of IG beams in ocean turbulent channels, we systematically study the transmission characteristics of IG and Gaussian beams in simulated ocean turbulent channels. The results provide a reference for IG beams to be applied in underwater laser communication.

The transmission and communication experimental platforms of IG optical signals in simulated ocean turbulent channels are designed and built. The platform can simulate ocean turbulence with different intensities by changing parameters such as water injection height, water temperature, and salinity. Firstly, the intensity scintillation index, centroid drift, and detector received power of IG beams and Gaussian beams are experimentally compared under different ocean turbulence intensity channels. Then the waveform distortion characteristics of the modulated signals of the two beams are further studied by modulating the square wave signals of 0.5–3 MHz frequency. Finally, the communication performance evaluation experiment of IG and Gaussian beams is carried out by loading modulation 7.5 Mbit/s signals with field programmable gate array programming. According to the above comparative results, the transmission and communication characteristics of IG beams in ocean turbulent channels are obtained.

The underwater transmission and communication performance of IG beams and Gaussian beams are compared, including scintillation index, centroid drift, power jitter variance, waveform distortion, and the bit error rate (BER). When the water temperature increases from 40.1 ℃ to 60.2 ℃, the performance advantage between the scintillation index of the IG beams and Gaussian beams increased from 15.5% to 21.8%. The performance advantage between centroid drift increased from 11.6% to 18.3%. However, compared with the Gaussian beams, the power jitter variance performance advantage of the IG beams reduced from 12.9% to 3.7%. The performance advantage between the waveform distortion of the square wave signal of the IG beams at the modulation frequency of 3 MHz decreases from 6.3% to 5.6% when the water temperature increases. Compared with Gaussian beams, the communication systems with IG beams as carriers have better BER performance. When the BER is 3.8×10^-3 (forward error correction threshold), the communication performance of IG beams in three kinds of underwater channels is better than that of Gaussian beams. The communication performance of the IG beam is improved by 0.8 dB at most in channels with different water injection heights, improved by 4 dB at most in channels with different temperatures, and improved by 2.5 dB at most in channels with different salinity. Moreover, the communication performance advantages of IG beams compared with Gaussian beams enhance with the increase in water injection height, temperature, and salinity.

The results of transmission experiments show that the scintillation index, centroid drift, and power jitter of the IG beams are better than those of the Gaussian beams. With the increase in ocean turbulence intensity, the improved ability of scintillation index and centroid drift of IG beams is enhanced, while the improved ability of power jitter is decreased. In different simulated ocean turbulence, the distortion of the modulated square wave of IG beams is lower than that of the Gaussian beams at the same frequency. The experimental results show that, when the BER is 3.8×10^-3, the communication performance of IG beams in channels with different water injection heights, different temperatures, and different salinity is 0.8 dB, 4 dB, and 2.5 dB higher than that of Gaussian beams, respectively. In summary, IG beams have a unique advantage in transmission and communication characteristics compared with Gaussian beams in ocean turbulent channels.