基于蒙特卡洛法的水下无线光传输特性分析

水下无线光传输面临功率衰减和时域宽度变大的问题,蓝绿光长距离传输特性更难以测试。利用蒙特卡洛法对水下蓝绿高斯光束传输过程进行仿真,分析海水类型、传输距离和发散角等因素对接收功率及脉冲响应的影响,数值对比小发散角情况下不同海水类型和传输距离的接收面上功率分布。结果表明,随着海水衰减系数、传输距离和发散角的增加,接收功率逐渐减小,时域宽度扩展变大。其中浑浊港湾海水在10 m以上传输距离时,接收功率受发散角的影响微乎其微,而时域宽度随发散角的增加由0.32 ns变为0.8 ns。虽然传输距离相差一倍,纯海水和清澈海水功率相似度依然高达99%。基于海水衰减系数的差异性,利用功率相似度和面积比来研究水下长距离的传输,可高效快速地获得长距离传输特性。

Analysis of Underwater Wireless Optical Transmission Characteristics Based on Monte Carlo Method

Underwater wireless optical transmission faces the problems of power attenuation and time domain width enlargement,the long-distance transmission characteristics of blue-green light are also more difficult to test.Monte Carlo method is used to investigate the process of underwater Gaussian beam,the effects of channel parameters such as water type,attenuation distance and divergence angle on the received power and impulse response are taken into account,power distribution on the receiving surface with different seawater types and transmission distances under small divergence is also numerically compared.The simulation results show that the received power decreases gradually and the time-domain width expands greatly with the increase of seawater attenuation coefficient,attenuation distance and divergence angle,among them,the influence of divergence angle on the transmission distance of turbid harbor water above 10 m is small,while the width of time domain changes from 0.32 ns to 0.8 ns with the increase of divergence angle.Although the transmission distance is doubled,the power similarity is still up to 99%in pure sea water and clear ocean water.Then based on the difference of seawater attenuation coefficient,we propose the power similarity and area ratio to analyze underwater long-distance transmission,so as to obtain the long-distance transmission characteristics more efficient and quicker.