激光光束在海水中的空间传输特性分析

由于激光的初始发散角以及海水对光的散射作用,激光在水下传输时光斑大小发生改变,从而影响接收机的接收范围。采用波长为514 nm的蓝绿激光,基于水下无线光通信信道模型,模拟光子在海水中的传输过程,通过统计不同传输距离时的光子数和光子位置,建立了海水信道中的光斑扩展模型,分析了海水水质对高斯光束的光斑空间特性的影响。结果表明:高斯光束在海水信道中传输时,根据光强比值定义光斑大小的位置,1/e光斑半径与传输距离呈线性关系,线性增加系数为光源的发散半角；当接收机灵敏度为确定值时,传输较短距离后光斑逐渐减小；光斑大小由接收机灵敏度决定,随着接收机灵敏度的增加,在相同距离下,接收到的光斑大小基本呈线性增加。

Analysis of spatial transmission characteristics of laser beam in seawater

Due to the initial divergence angle of laser and the scattering of light in seawater,the size of laser spot in undersea transmission is changed,and the reception range is affected.The photons of laser with a wavelength of 514 nm transmission process is simulated in seawater base on the undersea wireless optical communication channel model.The spot expansion model in seawater is established by statistical photon number and photon position in different transmission distance,then the effect of seawater quality on the speckle space characteristics of Gaussian beam is analyzed.The results show that when the position of the light spot size is defined as intensity ratio,there is a linear relationship between the 1/e laser spot radius and transmission distance when the Gaussian beam transmission in the seawater,and the linear increase coefficient is the divergence half angle of laser source;when the receiver sensitivity is determined,the light spot decreases after a short distance;the light spot size is determined by the receiver sensitivity.With the increase of the receiver sensitivity,the size of the spot received is linearly increased at the same distance.