亚波长衍射微透镜的设计

设计了连续浮雕衍射微透镜和与其等效的二元亚波长衍射微透镜,采用旋转体时域有限差分法对通过计算机辅助设计出的元件进行了严格的矢量分析,给出了各元件在焦平面的场强分布.分析结果表明,本文设计的二元亚波长微透镜对连续浮雕微透镜有很好的等效效果；填充因子的脉冲宽度调制法要优于填充因子的线性近似法；制作相对误差不大时深度误差和宽度误差对微透镜聚光能力的影响不大.

Design of Subwavelength Diffractive Microlens

The design procedure of subwavelength diffractive microlenses was presented based on the combination of scalar diffractive theory and effective medium theory. As examples continuous-relief microlenses and their counterparts of binary subwavelength diffractive microlenses were designed with computer code. Pulse-width-modulated approximation and linear approximation were employed to determine the width of subwavelength features. Body-of-revolutionary finite-difference time-domain method was used for the analysis of the designed microlenses to test whether the binary subwavelength profile can achieve effects similar to continuous-relief profile and effect of fabrication error on microlens ability of focusing optical energy. The electric field distributions on the focal planes of designed microlenses were illustrated. The numerical results showed that the designed binary subwavelength microlenses have nearly equal ability of focusing optical energy with the continuous-relief microlenses they simulated,the pulse-width-modulated approximation method has better efficiency than the linear approximation method,and the fabrication depth error and width error have little effect on microlens efficiency of focusing optical energy when the relative error is small.