面向光信息存储的小尺寸光场研究进展

Abstract

Significance The big data era has witnessed a significant increase in data volume, necessitating additional storage devices to handle the continuous growth in information. Highdensity optical storage technology offers advantages such as noncontact operation, resistance to electromagnetic interference, and high storage density, suggesting an excellent solution for storing, processing, and analyzing big data. However, traditional optical storage technologies encounter limitations regarding storage density improvement 1813012 -21 特邀综述 第 50 卷 第 18 期/2023 年 9 月/中国激光 owing to the diffraction limit, which restricts the size of recording points. Progress Advancements on the diffraction limit to improve optical storage density represent an important research topic. However, the reported nearfield optical storage techniques require evanescent wave detection, which requires precise motion control during optical writing. Additionally, it is difficult to form multilayer structures, which limits the increase in storage capacity. Recently, the development of multiparameter optical field modulation technology has enabled the creation of novel small light field structures under the tightly focusing of high numerical aperture objectives. This advancement can be used to generate small sized recording points, which provides new possibilities for achieving highdensity optical storage. This study focuses on the latest advancements in optical field modulation technology, particularly in tight focusing. It includes theoretical designs, simulations, experiments, efficient generation devices, and spatial tighter focal field applications.The study highlights the significance of smallsized subdiffraction focal spots for improving optical storage density. It discusses light field modulation theory, including mathematical descriptions of optical diffraction and the focal spot size limit. Diffraction depictions such as scalar and vectorial diffraction theories, along with the concept of optical superoscillation, are explored to address the diffraction limit and achieve superresolution focal spots. Scalar diffraction theory is a simplified form of vectorial diffraction theory. The latter has further applicability and provides higher precision in optical calculations. In contrast to scalar beams, vector beams consist of more complex light field distributions and are better suited to address the diffraction limit to generate smaller focal spots. This study also examines the sidelobe size variation concerning the main lobe size. Generally, as the main lobe size decreases, the strength of the sidelobe increases. When the size of the main lobe meets the superoscillation criterion (0.38 λ/NA), the sidelobe ratio is 16.2%. At this point, the intensity of the sidelobe maintains a good balance with the main lobe size, and its effect on the actual focused spot is negligible, which is acceptable for practical application.Furthermore, new optical field structures and modulation technologies are introduced, featuring the excellent focusing performance of cy...