离轴椭圆矢量光场传输中的光斑演变∗

摘要

对离轴椭圆矢量光场的传输特性进行了研究。推导出离轴椭圆矢量光场在自由空间传输电场和光强的解析表达式。数值分析结果表明，离轴高阶圆柱矢量光场具有非对称的光强分布，传输后的光强分布由传输距离、错位位移、椭圆率决定。在传输过程中除了光斑会展宽外，光场中的暗斑会逐渐消失，最终趋于一种稳态光强分布；相对于初入射平面的椭圆光斑，稳态椭圆光斑长短轴互换了。研究结果有助于深入理解离轴情况下椭圆矢量光场的动态传输特性，同时可以指导实际椭圆矢量光场的校准。%The propagation characteristics of the off-axis ellipse vector beam (OEVB) are studied in this paper. The analytic expressions of the electric field and the intensity after OEVB propagating in free-space are derived. Numerical results indicate that the intensity distribution of OEVB is asymmetric and the intensity distribution after propagating is determined by propagation distance, dislocation displacement and ellipticity. In addition to expanding, the intensity distribution of OEVB tends to steady-state distribution finally and the dark core of vector beam disappears gradually during propagation. The major axis and minor axis of the ellipse intensity distribution in the steady-state are exchanged with each other as compared with in the initial plane. The results can help us to understand the dynamic propagation characteristics of the ellipse vector beam under the off-axis situation, and they can also guide the calibration of the ellipse vector beam in practice.