一维光子晶体负折射透镜的柱矢量光束焦场调控

发布时间：2019-04-16 15:53

【摘要】：柱矢量光束具有独特的光强和偏振分布,其亚波长聚焦具有特殊的性质和广泛的应用,科研工作者们已经提出了许多不同的实现和调控方法,然而现有的各种方法都存在一定的局限性。传统的透镜难以实现更加紧致的聚焦且调控焦场的灵活性较低,因此研究热点转向了微结构领域。柱对称的等离激元透镜可以聚焦柱矢量光束的径向分量,并且具有器件集成度高的优势,但具有偏振态的局限性。为了拓宽柱矢量光束聚焦的应用领域,需要实现突破聚焦光束偏振态的限制的紧聚焦,并对焦场进一步灵活调控。本文基于一维光子晶体理论,利用其在第二能带对正交偏振态同时有效的负折射效应,设计出柱对称的一维光子晶体平凹透镜结构实现对柱矢量光束各偏振分量的同时亚波长聚焦。进一步通过改变柱矢量光束的偏振组分和剪裁平凹镜的出射表面形貌,使焦场的横向和纵向场分布得以灵活调控。并基于此,首次提出一维光子晶体平锥透镜结构,实现了具有长焦深特性的光针和光管形貌的特殊焦场。其中,光针焦场的横向半高宽达到了理论上的极小值0.36λ。并且,焦场的焦深可以通过改变器件尺寸得到灵活地调控。在一维光子晶体的工作基础上,进一步地借助负折射效应衍生出一种均一介质结构,即负折射率介质栅透镜,对柱矢量光束的聚焦及焦场调控进行研究,实现了上述的聚焦现象及调控效果。本文的工作为柱矢量光束的亚波长调控方式提供了新的切入角度,拓展了负折射率材料一维光子晶体和光栅透镜在柱矢量光束调控领域的应用,可供光学显微、微纳光学加工、光学微操纵等应用领域提供理论参考。
[Abstract]:Cylindrical vector beam has unique intensity and polarization distribution, and its sub-wavelength focusing has special properties and wide applications. Researchers have proposed many different realization and control methods. However, the existing methods have some limitations. It is difficult for the traditional lens to achieve more compact focusing and the flexibility of controlling the focal field is low, so the research focus turns to the micro-structure field. The cylindrical symmetric equidistant exciton lens can focus on the radial component of the cylindrical vector beam, and has the advantage of high integration of devices, but has the limitation of polarization state. In order to extend the application field of wide-column vector beam focusing, it is necessary to achieve tight focusing beyond the limit of polarization state of focused beam, and further flexible control of focal field is needed. In this paper, based on the one-dimensional photonic crystal theory, we use the negative refraction effect of the second band to the orthogonal polarization at the same time. A cylindrical symmetric one-dimensional photonic crystal flat concave lens structure is designed to focus each polarization component of cylindrical vector beam at the same time. Furthermore, the transverse and longitudinal field distribution of the focal field can be flexibly controlled by changing the polarization component of the cylindrical vector beam and the shape of the exit surface of the trimmed concave mirror. Based on this, the flat cone lens structure of one-dimensional photonic crystal is proposed for the first time, and the special focal field of the optical needle and tube with the characteristics of long focal depth is realized. Among them, the transverse half-width of the focal field of the optical needle reaches the theoretical minimum of 0.36 位. Moreover, the focal depth of the focal field can be flexibly adjusted by changing the size of the device. Based on the work of one-dimensional photonic crystal, a kind of homogeneous dielectric structure, called negative refractive index dielectric grating lens, is derived by means of negative refraction effect, and the focusing and focal field regulation of cylindrical vector beam are studied. The focus phenomenon and the control effect are realized. The work in this paper provides a new cutting angle for the sub-wavelength control of column vector beam, and extends the application of negative refractive index material one-dimensional photonic crystal and grating lens in the field of column vector beam control, which can be used for optical microscopy, micro-nano optical processing, and so on. The application fields of optical micro-manipulation provide theoretical reference.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O734;O436.3

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