复杂电磁波的动量密度  

Momentum density in complex electromagnetic waves

作　　者：董正高 DONG Zheng-gao(School of Physics,Southeast University,Nanjing,Jiangsu 211189,China)

机构地区：[1]东南大学物理学院,江苏南京211189

出　　处：《大学物理》2022年第12期26-30,35,共6页College Physics

基　　金：国家自然科学基金(12174052)资助。

摘　　要：对均匀平面电磁波的情况,坡印廷矢量所描绘的纵向传播动量图像清晰、简明.但对于具有涡旋相位或非均匀偏振态的复杂电磁波来说,坡印廷矢量能体现更丰富的动量内涵.本文基于电磁波的相量表达方法,从坡印廷矢量出发,在傍轴情况下分析了复杂电磁波的纵向传播动量以外的横向轨道动量、横向自旋动量,列举了几种典型电磁波中不同物理起因的横向动量特征,并结合相位分布图像进行了解释.Poynting vector clearly,as well as simply,describes the longitudinal propagation momentum in homogeneous plane waves.However,for complex electromagnetic waves with vortex phase or inhomogeneous polarizations,Poynting vector can exhibit more characteristics about the momentum density.Based on the phasor representation,we decompose the Poynting vector into orbital and spin momenta,in addition to the usual longitudinal momentum,and paraxially discuss the characterisitcs of transverse orbital momentum and spin momentum,by listing some cases of typical complex electromagnetic waves with physically different transverse flows,which are also explained by corresponding phase gradient pictures.

关 键 词：坡印廷矢量 动量密度 轨道动量 自旋动量 复杂电磁波 

分 类 号：O4-1[理学—物理]