Li Yunxiang, Wang Chuan, Zhao Xiaonan, Xu Feng, Wang Chinhua
Opt Express. 2018 Aug 6;26(16):21141-21152. doi: 10.1364/OE.26.021141.
Conventional photon sieves suffer from large chromatic aberration due to diffractive nature and can image only at a single designed wavelength with near zero bandwidth. Here, a novel photon sieve that can image achromatically and simultaneously at multiple wavelengths with wide spectral bandwidth is proposed and demonstrated experimentally. The multispectral achromatic imaging with a single diffractive photon sieve is implemented with harmonic diffraction and wavefront coding, in which harmonic diffraction makes different diffracted orders of multiple harmonic wavelengths on a common focus while wavefront coding through the coded distribution of the pinholes expands the bandwidth of diffracted imaging. Numerical simulations show that when four spectral bands centered at 437.5, 500, 583.3, and 700 nm in the visible range is designed with a cubic wavefront coding parameter α = 30π and a harmonic diffraction order of 5, the bandwidth at the corresponding wavelength band can reach ± 8, ± 9, ± 11 and ± 14 nm respectively, and the total working bandwidth of the harmonic diffraction wavefront coded photon sieve reaches ~84 nm compared with 0.39 nm of the conventional one. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieve of a focal length of 500 mm and a diameter of 50 mm at a designed wavelength of 700 nm. The results show excellent agreement with the theoretical predictions.
传统光子筛由于其衍射特性而存在较大的色差，并且只能在单个设计波长下成像，带宽几乎为零。在此，我们提出并通过实验证明了一种新型光子筛，它可以在宽光谱带宽下实现多波长消色差同时成像。利用谐波衍射和波前编码实现了单衍射光子筛的多光谱消色差成像，其中谐波衍射使多个谐波波长的不同衍射级在一个共同焦点上汇聚，而通过针孔的编码分布进行波前编码则扩展了衍射成像的带宽。数值模拟表明，当在可见光范围内设计四个以437.5、500、583.3和700 nm为中心的光谱带，立方波前编码参数α = 30π且谐波衍射级为5时，相应波长带的带宽分别可达±8、±9、±11和±14 nm，与传统光子筛的0.39 nm相比，谐波衍射波前编码光子筛的总工作带宽达到约84 nm。使用紫外光刻制造的焦距为500 mm、直径为50 mm、设计波长为700 nm的波前编码光子筛进行了实验验证。结果与理论预测高度吻合。
