湍流吸收海水中多相移键控调制理想涡旋光子的传输特性  

Transport Properties of Multiple Phase Shift Keying Modulated Perfect Optical Vortex in Turbulent Absorbing Seawater

作　　者：闫庆泽 张逸新[1] 朱云[1] YAN Qingze;ZHANG Yixin;ZHU Yun(School of Science,Jiangnan University,Jiangsu 214122,China)

机构地区：[1]江南大学理学院,江苏无锡214122

出　　处：《光子学报》2022年第11期108-116,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(No.61871202)。

摘　　要：通过建立理想光学涡旋光子所携带轨道角动量模的平均误码概率和信息容量的光传输系统模型,研究了弱湍流光谱吸收海水中多相移键控调制下理想光学涡旋光子的传输特性。基于光传输系统中轨道角动量模的平均误码概率和信息容量模型的数值计算,分析了调制阶和信道参数对理想光学涡旋光子传输的影响。数值研究表明:随着水体虚折射率的增加,光传输系统的平均误码概率和链路信息容量减小。采用更大的环半径和更高的发射功率,可以实现以理想光学涡旋光子为信号载体的水下光传输系统的高信息容量和低平均误码概率的信息传输。最后,通过对该模型的数值分析,得出了平均误码概率和信息容量同时受信号波长和海水吸收系数影响的结论。Since Orbital Angular Momentum(OAM)mode can form an infinite N qubit basis,it provides a new coding scheme for communication links.However,ocean turbulence and other external disturbances can cause phase disturbance of OAM mode,which generates the cross talk between the energy states of OAM modes.The self-focusing property of POV is beneficial to the transmission of OAM modes.The transmission quality of POV beams in oceanic turbulence is most related to the beam radius,while it is nearly free from the wavelength,topological charge,and radius-thickness ratio.Because of these special characteristics,POV has attracted wide attention of researchers.Moreover,the absorption of seawater reduces the information carrying capacity of POV photons and weakens the reliability of the system.Therefore,it is necessary to study the absorption of seawater and the transmission characteristics of POV.In addition,the modulation of POV also increases the information capacity carried by the POV′s OAM mode.In this paper,the ABEP and information capacity of underwater optical transmission system based on POV carrier and M-PSK modulation are studied under weak absorption turbulence.The wavelength dependence of fading channel is especially considered.The fading channel consists of two parts:signal energy loss caused by seawater turbulence and seawater absorption.Under the condition of paraxial transmission and Rytov approximation,the closed expressions of mean signal-to-noise ratio and signal error probability for M-PSK OAM channel are derived.Considering that the number of OAM signal level channels in common use is far less than the number of OAM topological charge(energy level)of POV vortex carrier,the concept that POV vortex carrier communication link is a symmetric link composed of multiple OAM level channels is proposed.Using the derived expression of ABEP of M-PSK OAM channel and the concept of symmetric link of multi-OAM channel,a novel closed-form expression of ABER and average capacity under various modulation schemes is propose

关 键 词：理想涡旋光 光学轨道角动量 光谱吸收海水 湍流效应 信息容量 调制 

分 类 号：TN929.1[电子电信—通信与信息系统]