基于表面等离子体波前操控的近场成像分辨力增强原理方法研究

Superlens, as one of the near-field super resolution imaging schemes, enables to overcome the diffraction limit of conventional optical system. However, increase of superlens’ working distance brings a sharp reduction of resolution. Particularly, the accessible range of working distance is ultra small for deep subwavelength resolution, putting superlens superresolution imaging technique in a dilemma. Here, we propose a method to modulate the imaging spatial spectra by SP wave front engineering and enhancing the evanescent imaging information, which compensates the exponential decay of evanescent waves and brings the enhancement of imaging resolution. This project would focus on applying the SP wave front engineering to the deep subwavelength imaging and achieve the significantly elongated working distance of plasmonic lens. The influence factors and principle to the transfer ability of evanescent wave, the imaging resolution and the imaging quality by SP wave front engineering would be investigated. The analytical model to characterize the physical mechanism of this method would be given. The structure for SP wavefront engineering and imaging would be designed, fabricated and tested by specially built experiment setup. The project would provide a new route to design the deep subwavelength resolution plasmonic lens with considerably elongated working distance and the proposed principle, and could be applied to near field microscopy, near-field lithography, high-density optical recording, etc.

以表面等离子体(surface plasmon,SP)超透镜为代表的近场成像突破了传统光学衍射极限，但面临工作距极短，工作距延伸分辨力急剧下降的难题，极大限制了其应用推广。本项目提出通过操控SP波前传输波矢、位相、极化等特性，大幅延伸工作距，增强亚波长信息成像传递能力，弥补倏逝波指数衰减规律，显著提升对比度和分辨力。项目主要研究SP波前操控方法，厘清SP波前操控对深亚波长成像分辨力、工作距等影响因素和规律，建立相应模型和设计、加工方法，搭建实验系统，完成验证效果。本项目结果有望解决近场超分辨成像工作距极短、分辨力低的共性关键科学技术难题，为近场成像提供分辨力增强原理方法，在近场显微、近场光刻以及近场光存储等领域具有重要应用前景。

以表面等离子体(surface plasmon,SP)超透镜为代表的近场成像突破了传统光学衍射极限，但面临工作距极短，工作距延伸分辨力急剧下降的难题。本项目提出通过操控SP波前传输波矢、位相、极化等特性，大幅延伸工作距，增强亚波长信息成像传递能力，弥补倏逝波指数衰减规律，显著提升对比度和分辨力。项目主要研究了SP波前操控对深亚波长成像分辨力、工作距等影响因素和规律，建立相应模型和设计、加工方法，搭建实验系统，完成验证效果。主要研究结果如下。. 1）提出延伸焦深和工作距的SP超分辨成像方法。采用棱镜浸没离轴光束激发横向波矢表面波，照明SP共振腔透镜，实现成像焦深和工作距显著延伸。例如，设计和验证了对于线宽1/6波长、1/10波长图形，拓展工作距到1/9波长~1/3波长，是传统近场成像方法4~8倍。. 2）开展了SP成像焦深和工作距延伸实验验证。搭建了成像实验装置，采用光刻胶记录方式，验证了在1/6波长、1/8波长线宽分辨力下的成像工作距延伸能力。. 3）提出和实验验证了辅助边缘结构修饰的SP超分辨成像方法。采用在线条图形出射面加入浅沟槽的方法，对离轴照明情况下的离散图形以及边缘图形畸变进行修正，实验上证明了边缘线条的拓宽效应被显著抑制，提高了离轴照明下SP超分辨成像的图像质量和兼容性。