用三区三元相位滤波器提高近场光存储系统的焦深

Increasing focal depth of near-field optical storage systems by a three-zone ternary phase filter

为了提高近场固体浸没透镜光存储系统的焦深,设计了三区三元相位滤波器。设计建立在矢量衍射理论基础上,应用MATLAB优化工具箱优化设计出可以获得最大焦深的滤波器结构参数。在设计过程中,我们限定记录光斑的大小与没有滤波器时的光斑大小相等,而光斑的强度减小一半,所设计的滤波器可以使近场固体浸没透镜光存储系统的焦深提高1.6倍。同时,也与三区二元相位滤波器进行比较,在光斑大小和光斑强度相同的条件下,焦深也有所增加。这说明在近场固体浸没透镜光存储系统中三区三元相位滤波器具有比三区二元相位滤波器更优越的特性。

Based on the vector diffraction theory and by using the optimizing toolbox in MATLAB,a three-zone ternary phase filter is designed to increase the focal depth of a near-field solid immersion lens optical storage system.In the process of design,the spot intensity is constrained to half of the spot intensity without a filter and the spot size is constrained to equal to the spot size without a filter.When the designed filter is applied a SIL near-field optical storage system,it can improve the focal depth by 1.6 times.At the same times,compared with an optimally designed three-zone binary filter,the focal depth also increased obviously on the condition of identical spot size and intensity.These results are useful to near-field high-density optical storage.