相干探测系统中的混频效率  

Mixing Efficiency in Coherent Detection System

作　　者：谭振坤 柯熙政[1] 

机构地区：[1]西安理工大学自动化与信息工程学院,陕西西安710048

出　　处：《激光与光电子学进展》2017年第10期120-128,共9页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(61377080;60977054)

摘　　要：在自由空间相干光通信系统中,混频效率直接反映相干探测灵敏度。分别推导了混频效率随光轴径向误差、失配角、轴向离焦和大气湍流强度变化的表达式,并进行了仿真分析。结果表明:选择与波长匹配的束腰半径和相对孔径可使混频效率达到最大值0.8145。信号光与本振光的光轴径向误差对混频效率和相对孔径的影响最大,接着是失配角和轴向离焦。将以上3种影响因素分别限制在0~4μm、0~0.05rad、0~200μm范围内,当选取1550nm的光波作为通信波长且束腰半径为3.4λ、相对孔径为0.21时,混频效率可达到0.55以上。在中强湍流条件下,使用小口径接收天线能有效抑制大气湍流效应。The coherent detection sensitivity can be directly reflected by mixing efficiency in free-space coherent optical communication system. Expressions of the variation in mixing efficiency with the radial error of optical axis, mismatching angle, axial defocusing and atmospheric turbulence intensity are derived respectively, and simulation analysis is carried out. Results show that mixing efficiency can reach the maximum value of 0. 8145 when we choose the waist radius and relative aperture matched with wavelength. The optical axis radial error of signal light and local oscillator light has the greatest influence on the mixing efficiency and relative aperture, followed by the mismatching angle and axial defocusing. The above three factors are limited to 0-4 λm, 0-0.05 rad and 0-200μm respectively. Mixing efficiency is larger than 0.55 when the 1550 nm light wave is chosen as the communication wavelength, the waist radius is 3.4λ and relative aperture is 0.21. The atmospheric turbulence effect can be effectively suppressed with a small aperture receiving antenna under the mid-strong turbulent condition

关 键 词：光通信 空间相干光通信 混频效率 相干探测 相对孔径 大气湍流 

分 类 号：TN929.1[电子电信—通信与信息系统]