大数值孔径光子筛偏振特性研究

根据角谱理论建立不同偏振照明条件下的光子筛矢量衍射模型。在此基础上,对入射光分别为线偏振光、径向偏振光、切向偏振光三种特殊偏振状态下的光子筛聚焦光强分布进行了模拟分析。研究结果表明,对于大数值孔径光子筛,入射光的偏振特性将对光子筛聚焦光强分布产生巨大影响。线偏振光将使聚焦光斑沿偏振方向拉伸,切向偏振光产生的聚焦光斑具有"中空"结构,而径向偏振光所产生的聚焦光斑呈较为规则的圆形,且其焦深优于线偏照明情况。在激光直写及高分辨成像等光子筛典型应用中采用径向偏振照明将进一步提高系统分辨力。

Polarization Property of Photon Sieves with High Numerical Aperture

Vector diffraction model of photon sieves with different polarized illumination is built based on angular spectrum representation. Simulations are carried out to analyze the intensity of photon sieves, focal spot when polarizations of incident planar beams are linear, radial and tangent, respectively. Result shows that the polarization property of incident beams makes huge influence on the focal spot of photon sieves with high numerical aperture. With linearly polarized beams, the focal spot extends in the polarized direction. By using tangent polarization, there is a dark hole in the center of the focal spot. The focal spot of radially polarized beam has a form of a circle and the focus is deeper. In laser lithography systems and imaging systems, resolution power can be improved by using radially polarized beam as the incident beam of photon sieves.