孔洞式偏振不敏感红外超构透镜  

The holes modified infrared polarization-free metalens

作　　者：伏开虎 田雪 FU Kaihu;TIAN Xue(Beijing Institute of Remote Sensing Equipment,Beijing 100854,China)

机构地区：[1]北京遥感设备研究所,北京100854

出　　处：《光学技术》2024年第5期594-597,共4页Optical Technique

摘　　要：超构透镜通常由矩形、椭圆形或圆形柱状微结构按设计要求的相位有序排布,由于单元柱的结构尺寸为亚波长级,单元柱高度和长宽(或直径)之比往往大于5,加工制备难度大,特别是对于激光直写这种无需掩膜版、加工自由度高的微纳加工方式,其加工精度还难以满足对复杂阵列的单元柱进行加工的需求。而激光直写在开孔洞方面的加工精度和工艺稳定性要明显优于雕刻微柱阵列。因此,文章研究了一种孔洞式红外超构表面,不同于柱状的超构透镜组成方式,孔洞式超构表面通过单元孔洞的尺寸大小对入射光的相位进行调控,进而实现光学聚焦。加工完成的超构透镜由于孔洞周边连成一体,不易发生柱状超构表面的单元柱断裂、倒伏等现象。将孔洞式超构透镜开孔洞面朝光学系统内部,超构透镜另一面镀红外增透膜,可以同时提高孔洞式超构透镜的光学透过率和环境适应性。文章以硫化锌为基体,利用时域有限差分数值模拟软件FDTD Solutions探索了孔洞式超构透镜在长波红外9μm处,设计焦距为1mm时的聚焦性能,仿真结果表明孔洞式超构透镜聚焦效率高,具有良好的应用前景。Metalens are usually composed of rectangle, elliptical or circular micro/nano pillars arrayed with design phase. The manufacture of metalens is diffcult for the size of pillars is always subwavelength and the ratio of height to length/width(or radius) of pillar is usually bigger than 5. The machining accuracy of Direct Laser Writing(DLW) with high machining freedom and mask-free ability doesn't satisfy the manufacture of pillar type metalens. However, the accuracy of drilling holes and the process stability of DLW is much better than pillar fabrication. Thus, this paper introduces hole type metalens, in which the hole work as the unit cell with various radius to modify the optical phase to foucus. The periphery of hole type metalens is tightly connected as one net, which shows higher structure stability. The break of phase modified cell within pillar type metalens will rarely occure within hole type metalens. The deposition of anti-reflective(AR) film on the back of holes surface of metalens will enhance the transmittance of incident light and improve the harsh environment endurance as mounting this surface to the air and holes surface into the optical system. In this paper, the finite-difference time-domain(FDTD) was applied to the analysis of imaging ability of hole type metalens, which is designed with ZnS substrate, 9μm center wavelength, 1mm focal length. The simulation results show excellent focusabilty and well commercial value.

关 键 词：孔洞式 偏振不敏感 ZNS 超构透镜 

分 类 号：TN216[电子电信—物理电子学]