超短脉冲拉盖尔–高斯光束通过圆环后的光谱异常

Anomalous Spectral Behavior of Ultrashort Pulsed Laguerre-Gaussian Beams Diffracted by Circular Ring

摘要: 本文对超短脉冲拉盖尔–高斯脉冲光束通过圆环光阑后在远场的光谱移动和光谱开关以及临界衍射角附近的功率谱变化规律进行了研究。结果表明：在临界衍射角附近超短脉冲拉盖尔–高斯光束光谱分裂成两等峰值，即产生了光谱开关效应；随着脉冲宽度的增加，两等峰值之间的角频率间隔减小，光谱开关产生的位置向轴靠近，相对光谱移动减小；而随着圆环孔径的增大，光谱开关产生的位置发生变化，但相对光谱移动基本保持不变。

Abstract: The spectral anomalies of ultrashort pulsed Laguerre-Gaussian beams diffracted by a circular ring are studied. It is shown that the spectral is split into two peaks with equal height at the critical diffraction angle θc, this phenomenon is referred to as spectral switch. With increasing pulse duration, the frequency difference between the two equal heights of the spectral switch decreases and the critical position, where the spectral switch taking place is closer to the z axis and the relative spectral shift decreases. And with increasing the size of the circular ring increases, the relative spectral shift remains.