Unidirectional ultrabroadband and wide-angle absorption in graphene-embedded photonic crystals with the cascading structure comprising the Octonacci sequence
Unidirectional ultrabroadband and wide-angle absorption in graphene-embedded photonic crystals with the cascading structure comprising the Octonacci sequence
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DOI：
10.1364/josab.399048
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发表时间：
2020-09-01
影响因子：
1.9
通讯作者：
Zhang, Haifeng
中科院分区：
文献类型：
--
作者：
Guo, Sijia;Hu, Caixing;Zhang, Haifeng
利用传递矩阵方法，在太赫兹波段由周期序列和准周期Octonacci序列形成级联结构排列的石墨烯嵌入光子晶体（GPCs）中实现了具有超宽带吸收带宽和角稳定性的单向吸收体。因此，石墨烯片的表面电导率可以通过化学势来调节，并且所提出的吸收剂的特性是可调的。与不同周期序列拼接的结构相比，所提出的复合结构的相对吸收带宽高达94.53%，远远超过周期序列拼接的结构。对比了Octonacci序列、Fibonacci序列和twe - morse序列，计算结果显示了Octonacci序列在扩展吸收带宽方面的优势。在相关参数优化的情况下，入射波主要在正向传播中被反射，在TM模式下在反向传播中被大范围吸收，表现出极好的单向性和角稳定性。研究了化学势、结构厚度和堆数对吸光性能的影响。此外，还引入了阻抗匹配理论和干涉场理论来解释GPCs的本征吸收机理。总之，单向宽带角度不敏感吸收体在光传感、光滤波、光探测、太阳能收集等方面具有广泛的应用前景。(C) 2020美国光学学会
Using the transfer matrix method, a unidirectional absorber with an ultrabroadband absorption bandwidth and angular stability is realized in the graphene-embedded photonic crystals (GPCs) arranged by the cascading structure formed with the periodic sequence and the quasi-periodic Octonacci sequence in the terahertz regime. As a result, the surface conductivity of the graphene sheet can be modulated via the chemical potential, and the characteristics of the proposed absorber are tunable. Compared to the structure spliced by the diverse periodic sequences, the relative absorption bandwidth of the proposed composite construction is up to 94.53%, which far outweighs that of the periodic one. We compare the Octonacci sequence, the Fibonacci sequence, and the Thue-Morse sequence, and the calculated results reveal the advantage of the Octonacci sequence in the expansion of the absorption bandwidth. Under the optimization of the related parameters, the incident wave is primarily reflected in the forward propagation and absorbed in a wide range of theta under the TM mode in backward propagation, which shows the splendid unidirectionality and angular stability. The impacts of the chemical potential, structural thicknesses, and stack numbers on the absorption properties are also investigated in detail. Additionally, the impedance match theory and the interference field theory are introduced to explain the intrinsic absorption mechanism of the presented GPCs. In short, the unidirectional broadband and angle-insensitive absorber has extensive application prospects in optical sensing, optical filtering, photodetection, and solar energy collection. (C) 2020 Optical Society of America