摘要
基于Rytov近似,理论推导了完美涡旋光束(PVB)经过大气湍流水平信道后的螺旋相位谱解析表达式,研究了大气湍流中光束波长、半环宽、发射处轨道角动量(OAM)模态、光束半径、近地面折射率结构常数以及湍流系数对OAM模态探测概率和串扰概率的影响。结果表明:随着发射处OAM模态、传输距离、光束半径、近地面折射率结构常数以及湍流系数的增加,经大气湍流传输后的探测概率下降;随着光束波长的增加,经大气湍流传输后的探测概率增加。此外,PVB在近场的探测概率几乎不随发射处OAM模态变化,而当光束传输到远场时,探测概率随发射处OAM模态变化明显,这是因为PVB传输到远场变成类贝塞尔光束,其光束半径随发射处OAM模态变化明显。
Objective Vortex beam is a beam that carries orbital angular momentum(OAM).The perfect vortex beam(PVB)is a new type of beam that has emerged in recent years.Compared with other traditional vortex beams,the PVB has the property that the radius of the optical ring does not increase with the increase in OAM mode,which has attracted much attention in the field of free-space optical communication.Moreover,the different OAM modes of the vortex beam are orthogonal to each other and can be used to expand the channel capacity of optical communication systems.The OAM dimension of the vortex beam can also be used for signal coding,and since the number of modes of OAM modes is not limited(it can be any integer),it is theoretically possible to carry an infinite amount of bits of information in a single code element.However,vortex beam transmission in the atmosphere will be affected by atmospheric turbulence and produce distortion,and atmospheric turbulence makes its light intensity distribution uneven.Spiral phase distortion can result in the expansion of the spiral spectrum,cause crosstalk between different modes of the vortex beam,and reduce the signal-tonoise ratio of the communication system,thus leading to the degradation of the communication quality in practical applications.In this study,based on the Rytov approximation,the analytical expression of the spiral phase spectrum of the PVB at the receiving aperture is derived,and the probability of detection and crosstalk probabilistic models of the OAM mode of the PVB is established.The effects of different parameters on the PVB in a turbulent atmosphere are analyzed in the context of the light intensity distribution characteristics of the PVB in free space transmission.These results are expected to provide a reference for the application of PVB in free-space optical communication.Methods In this paper,an analytical expression for the spiral phase spectrum of the PVB is derived theoretically.First,the complex amplitudes of PVBs transmitted in atmospheric turbulence in the
作者
李思瑶
丁洲林
侯春雨
王玮君
马佳欣
于永吉
Li Siyao;Ding Zhoulin;Hou Chunyu;Wang Weijun;Ma Jiaxin;Yu Yongji(Jilin Key Laboratory of Solid Laser Technology and Application,School of Physics,Changchun University of Science and Technology,Changchun 130022,Jilin,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2024年第6期34-41,共8页
Acta Optica Sinica
基金
吉林省自然科学基金(20210101154JC)。
关键词
大气光学
完美涡旋光束
轨道角动量
湍流大气
螺旋相位谱
atmospheric optics
perfect vortex beam
orbital angular momentum
turbulent atmosphere
spiral phase spectra
