消色差超构表面复合透镜

Achromatic metalens compund lens

超构表面因其体积轻薄易于集成化,有望在某些特定场合取代传统透镜实现多功能光学器件。超构表面的光束偏转角随波长的增加而增大,与传统折射透镜相比产生相反的色散,这种色散又被称为“异常色散”或“负色散”。理论上利用超构表面的负色散和传统折射光学器件的正色散相抵消,可以完全矫正光学系统的色差。由此出发,设计了一种基于光刻胶材料,由Pancharatnam-Berry(PB)相位型超构表面作为第一透镜,传统球面透镜作为第二透镜的消色差超构表面复合透镜,利用时域有限差分数值模拟软件FDTD Solutions探索了该透镜在780~980 nm波段的聚焦性能,证明了消色差光刻胶超构表面复合透镜优异的消色差效果。相对传统的消色差超构表面通过相位补偿来消色差的方法,这种消色差设计简单且高效,为特定波段内的消色差成像提供了一定的借鉴意义。

Metalens has the prospective to replace the traditional lens for multifunctional sub-wavelength imaging due to its thinness and ease of integration.The beam deflection angle of the metalens increases with the increase of wavelength and produces opposite dispersion compared to the traditional refractive lens.This form of dispersion is also called"abnormal dispersion"or"negative dispersion".Theoretically,the negative dispersion of the metalens and the positive dispersion of traditional refractive optical devices can be used to fully offset the chromatic aberration of the optical system.Consequently,this study demonstrates the design of an achromatic metalens compound lens based on photoresist material by employing Pancharatmane-Berry(PB)phase metalens as the first lens and traditional spherical lens as the second lens,through finite difference time domain method.The focusing characteristics of the lens atλ=780~980 nm are investigated by FDTD Solutions(a numerical simulation software)and an exceptional achromatic effect of photoresist metalens compound lens is realized.Compared with the traditional achromatic metalens,the achromatic design is simple and efficient which provides a certain significance for achromatic imaging in the specified bandwidth.