非傍轴矢量异常空心光束的传输特性

Propagation of nonparaxial vectorial anomalous hollow beams

将Cai提出的异常空心光束的理论模型推广到非傍轴范畴,推导出非傍轴矢量异常空心光束传输的解析表达式,用以研究它在自由空间中的传输特性。研究表明,异常空心光束在传输过程中光束形状会发生变化。与高斯光束不同,非傍轴异常空心光束傍轴近似成立条件依赖于传输距离,这与异常空心光束光强分布随传输距离的变化有关。非傍轴异常空心光束远场的光束质量可用桶中功率来描述,桶中功率随f参数(波长与束腰宽度的比值)的增大而减小。

The theoretical model of anomalous hollow beams proposed by Cai in the paraxial approximation is extended to the nonparaxial regime. The closed-form propagation expression for nonparaxial vectorial anomalous hollow beams in free space is derived and used to study their propagation properties in free space. It is found that anomalous hollow beams can not preserve their shape upon propagation, but the paraxial approximation condition for anomalous hollow beams additionally depends on the propagation distance, which is different from Gaussian beams. The far-field beam quality of nonparaxial vectorial anomalous hollow beams can be described by the power in the bucket（PIB）, which decreases with increasing the f parameter （the ratio between wavelength and beam maist width）.