基于光频超衍射材料的深亚波长穿透深度表面显微成像

Aiming to the difficulties of surface imaging for the specimen utilizing conventional imaging microscopy by reason of the noise from the deep region in specimen, this project is proposed to investigate the surface imaging microscopy with deep subwavelength penetration depth based on the metamaterials beyond the diffraction limit in the optical frequency region. Utilizing the characteristic of optical spatial spectrum band-pass filtering in metamaterials, large-area even surface plasmon field with deep subwavelength penetration depth can be achieved by combining with nano-scale gratings, which shows the potential to achieve surface imaging microscopy with 10nm penetration depth. According to structure optimization of surface plasmon wave source, it is numerically demonstrated that penetration depth down to 10 nm. In this project, the principle and mechanism of light propagation and optical spatial spectrum filtering in the layered metal–dielectric structure are need to be further investigated. The impacts of geometry parameters and structures of metamaterials on the optical spatial spectrum filtering are analyzed and demonstrasted. New surface plasmon wave source with better imaging performance would be optimized and fabricated. By loading the nano-scale thick dual-layer of fluorescent dye on the SP wave source compactly, far-field spectral analysis for measurement of the penetration depth would be investigated theoretically and demonstrated experimentally. The SP wave source structure of surface imaging microscopy for biologic cells would be proposed and demonstrated experimentally. This would provied a new rout to achieve the surface imaging microscopy with deep subwavelength penetration depth for cellular biology and material.

针对传统显微成像技术受样本深层区域噪声信号干扰，对样本表面成像困难的问题，本项目开展基于光频超衍射材料的深亚波长穿透深度表面显微成像研究，利用光频超衍射材料的空间频率带通滤波特性，结合纳米光栅来激发大面积均匀深亚波长穿透深度SP光场，有望实现10nm穿透深度的表面显微成像。课题组前期已初步开展光频超衍射材料空间频谱滤波特性规律分析，提出了实现深亚波长穿透深度的SP表层照明激发方法。本项目可通过进一步理论研究光频超衍射材料空间频谱滤波和传输的机理规律及影响因素，发展特定穿透深度SP光场激发结构的理论设计和数值优化方法；设计用于实现10nm穿透深度表层显微成像的SP光场激发结构；探索近场倏逝波穿透深度的双层荧光染料光谱远场检测方法，搭建光学检测系统完成对SP光场激发结构的光学检测和性能表征，进一步开展深亚波长穿透深度细胞生物表面显微的实验验证。

提出并证实了一种实现 50nm 以下，最低可至 10nm 的超短照明深度的表面成像显微技术。通过应用金属介质多层膜组成的双曲超材料，激发出存在多层膜内部的深亚波长 BPP 模式（bulk plasmon polariton，BPP）。.完成了深亚波长穿透深度的等离子体表面显微结构设计、器件制备及实验验证。我们通过纳米光栅激发具有较大横向波矢的单一BPP 模式，实现了超短照明深度的均匀照明场。通过改变激发光束的入射角度来调制单一BPP 模式的横向波矢，获得了不同穿透深度的表面照明场。此外，还将BPP 照明结构应用于针对被不同荧光分子淹没的表层荧光图形的表面成像。实验验证了具有超短穿透深度的照明场能够实现高对比度的表面成像。该方法在单分子探测和细胞科学中具有潜在应用。