部分相干光的轨道角动量及其谱的分析研究

Study on orbital angular momentum and its spectrum of partially coherent light beam

针对光束轨道角动量的研究主要集中在相干光束的研究,而对于部分空间相干光束的轨道角动量研究较少,依据部分相干光的Wigner分布函数推导出部分相干光的轨道角动量表达式,分析了部分相干光的轨道角动量谱特性。采用Mercer展开法得到了轨道角动量谱,计算了给定部分相干光束的轨道角动量谱,讨论了部分相干性对轨道角动量谱的影响。研究结果表明:部分相干光和相干光具有相同的轨道角动量表达式,部分相干光的轨道角动量谱随着相干性的变差而愈发弥散,携带轨道角动量的部分相干光束的轨道角动量谱比不携带轨道角动量的部分相干光束的轨道角动量谱更容易受相干度的影响。

Orbital angular momentum （OAM） of light beams attracted great attention recently due to its importance in theory and application. Most works on OAM of light beams were concenterated on coherent beams, and few efforts were made on partially （spatial） coherent beams （PCB）. The OAM of PCB was deduced from their Wigner distribution function, and the OAM spectra of PCB were analysed. The Mercer expansion method was used to obtain the OAM spectra of PCB. For given PCBs, their OAM spectra were carried out. The dependence of OAM spectra on the partial coherence was also discussed. We found that the OAM of the PCBs takes the same form as that of coherent beams, the OAM spectrum of PCBs disperses more seriously with the worse coherence, and the OAM spectrum of PCBs with zero total OAM is more vulnerable to bad coherence than that of the PCBs with non-zero total OAM.