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柱矢量光束具有柱对称性的偏振分布,其独特的光场分布和聚焦特性被广泛应用于光学微操纵及光学成像等领域,并迅速向亚波长尺度拓展.通常,亚波长尺度聚焦采用等离激元透镜实现,但存在光场调控的偏振态局限性.而借助光子晶体的负折射效应,不仅能够实现亚波长聚焦或成像,而且应对正交偏振态同时有效.采用对电磁波具有更强调控能力的一维金属光子晶体结构,计算得到的能带结构和等频曲线表明其负折射效应在特定波段对正交偏振态同时有效.在此基础上设计出一维金属光子晶体柱对称平凹镜结构,通过有限元算法模拟显示了可见光波段的径向和旋向偏振光的同时亚波长聚焦行为.进一步的结果表明,改变柱矢量光束的偏振组分能够直接有效地调节焦场空间分布及偏振分布特性.所提出的平凹镜结构能够实现对任意偏振组分的柱矢量光束的亚波长尺度聚焦,且该结构的设计对于各波段情况均有参考意义.该研究结果对小尺度粒子的光学微操纵、超分辨率成像等相关领域具有潜在的应用价值.
The columnar light beam has a column-symmetric polarization distribution, and its unique light field distribution and focusing characteristics are widely used in the field of optical micromanipulation and optical imaging, etc., and are rapidly extended to subwavelength scales. Generally, the subwavelength scale focusing uses a plasma However, with the negative refractive effect of photonic crystals, not only sub-wavelength focusing or imaging can be realized, but also the orthogonal polarization state should be effectively applied at the same time. Ability of the one-dimensional metal photonic crystal structure, the calculated band structure and the equipotential curve shows that the negative refraction effect in a particular band of orthogonal polarization state at the same time effective on this basis, the design of one-dimensional metal photonic crystal column symmetry flat concave Mirror structure and simulated by the finite element method to simulate the sub-wavelength focusing of both radial and rotational polarization in the visible wavelength band.Further results show that changing the polarization components of the beam can directly and effectively adjust the spatial distribution of the coke field and Polarization Distribution Characteristics The proposed plano-concave mirror structure enables the sub-wavelength scale of the column vector beam of any polarization component Coke, and the design of the structure for each band where the reference has significance. The results of the small scale of the optical micro-manipulation of particles, super-resolution imaging and other related art have potential value.