纳米成像器件光子筛的逆向设计与特性研究

The nano-focusing and nano-imaging from hard x-rays to extreme ultraviolet (EUV) region have given more and more attention at home and abroad. It will be of momentous practical significance for some special subject, such as photolithography technology, life science, environmental science, space science, materials science and the application fields of physics, and so on. However, refractive lenses are prevented from the imaging and focusing in these spectral regions because of strong absorption of solid materials. Based on geometrical optics and diffractive optics, we study both nano-focusing and nano-imaging properties of diffractive optical element photon seives, and the inverse optimized design by use of Monte Carlo method and iteration algorithm. Relative to ours previous work on focusing and imaging of photon sieves composed of different types of pinholes on condition of different numerical aperture, we extend the in-line focusing and imaging into off-axis case, which can be applied to amplitude or phase photon sieves. Off-axis imaging not only makes photon sieves have directional focusing and beam splitting functionality, but also deeply improves the flexibility of optical system design. Meanwhile, with the help of Monte Carlo and iteration algorithm, the inverse problem of photon sieves design is investigated in the case of electric filed distribution known. Furthermore, one of the goals is to realize beam shaping in spatial domain, which is very useful for laser system design. In temporal domain, beam splitting, beam shaping and filtering are studied for ultra-short pulse. Finally, we propose negative-focus diffractive optical element to compensate the strong dispersion of photon sieves. That proves some new accesses and methods for further broadband laser focusing and imaging of photon sieves.

硬x射线到极紫外波段的纳米尺度聚焦成像研究是目前国内外研究的热点，它对于光刻技术、生命科学、环境科学、空间科学、材料科学和物理学领域中的应用具有重要的实际意义。由于在该波段材料的强吸收，无法使用传统的折反式光学元件使其成像，本课题基于几何光学和衍射光学理论，开展光子筛的逆向优化设计和成像特性研究。基于不同数值孔径下不同孔型光子筛的聚焦成像理论，将振幅和位相型光子筛由同轴聚焦成像模型拓展至离轴聚焦成像，使得光子筛具有了定向聚焦和分束的功能，这一功能大大增强了光子筛在光学系统中的结构形式。基于蒙特卡罗和迭代算法，根据输出光场的空间分布，逆向反演光子筛的结构参数，并进行全局优化设计。开展光子筛时间域内对超短脉冲的分束、光束整形和滤波研究。最后针对纳米成像元件光子筛的高色散特性，提出采用具有负焦点的衍射光学元件补偿光子筛的强色散，为进一步开展光子筛的宽带光色散补偿技术研究与应用提供思路和理论依据。

硬x射线到极紫外波段的纳米尺度聚焦成像研究是目前国内外研究的热点，它对于光刻技术、生命科学、环境科学、空间科学、材料科学和物理学领域中的应用具有重要的实际意义。由于在该波段材料的强吸收，无法使用传统的折反式光学元件使其成像，本课题基于几何光学和衍射光学理论，开展光子筛的逆向优化设计和成像特性研究。基于不同数值孔径下不同孔型光子筛的聚焦成像理论，将振幅和位相型光子筛由同轴聚焦成像模型拓展至离轴聚焦成像，使得光子筛具有了定向聚焦和分束的功能，这一功能大大增强了光子筛在光学系统中的结构形式。基于蒙特卡罗和迭代算法，根据输出光场的空间分布，逆向反演光子筛的结构参数，并进行全局优化设计。通过引入斐波那契数列构造了广义斐波那契光子筛，成功实现了三维阵列聚焦和成像，即在不同层平面上同时产生二维阵列焦点或像点，其光学特性由序列的数学特征决定，这一特点大大拓展了光子筛在光学系统中的应用。