部分相干光经两个级联单缝衍射后的光谱变化及光谱开关现象

Spectral Changes and Spectral Switches of Partially Coherent Light Diffracted by Two Cascaded Slits

研究多色高斯-谢尔模型光束经两个单缝衍射后,其光谱变化及光谱开关现象.利用复高斯函数展开法,得到经两个单缝衍射后的衍射场中的交叉谱密度及光强表达式.通过数值计算,研究衍射场中轴上点和横截面处的光谱变化和光谱开关现象,以及相干长度对观察点光谱的影响.结果表明,对于随着传输距离的增加,轴上观察点将出现一些由"红移"到"蓝移"再到"红移"的变化过程.对于某一个横截面,轴上点的光谱变化及光谱开关现象最明显;随着观察点离轴距离的增加,光谱变化将减小.

The spectral changes and spectral switches of polychromatic Gaussion Schell-model beams diffracted by two cascaded slits were studied. Based on the expended method of complex Gaussion functions, the expression for the crossspectral density and intensity in the diffracted field was derived. The spectral changes and spectral switches for the on-axial observation point and in the cross section in the field was investigated by numerical simulations. It is found that with the increment of propagation distance, the spectrum may redshifted first, then blueshifted, and return to redshifted again for on-axial observation point. And for particular a cross section, the spectral changes and spectral switches is more clear for on-axial observation point, while as the distance between the point and the axis increase, the spectral changes are less clear,