Kim Beom-Jun, Kim Je-Min, Jo Min-Seung, Kim Sung-Ho, Yoon Jun-Bo
School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea.
Center for Bio-Integrated Electronics, Northwestern University, 633 Clark St, Evanston, IL, 60208, USA.
Sci Rep. 2024 Nov 14;14(1):28000. doi: 10.1038/s41598-024-79631-5.
An infrared (IR) absorber is a crucial component for thermal detectors, requiring high absorptance over a broad wavelength range while maintaining low heat capacity for optimal performance. Most thermal detectors use a thin film IR absorber that is suspended in air, supported by a layer beneath it for mechanical stability. However, this support layer increases heat capacity without contributing to IR absorptance, thereby reducing the performance of thermal detectors. In this paper, we introduce a polarization-independent nanowire array absorber using flanged nanowires with a C-shaped cross-section. This C-shaped design provides mechanical stability, eliminating the need for a support layer. Although nanowire array is generally known to exhibit polarization characteristics, the unique structure of the proposed flanged nanowires enables them to achieve polarization-independent properties, resulting in high absorptance similar to that of film absorbers. We theoretically analyzed the polarization-independent characteristics of the flanged nanowires using an optical circuit model and optimized the flanged nanowire structure using finite-difference time-domain (FDTD) simulations. Finally, we experimentally demonstrated the polarization-independent characteristics of the flanged nanowires and confirmed their high absorptance comparable to that of film absorbers.
红外（IR）吸收器是热探测器的关键部件，要求在宽波长范围内具有高吸收率，同时保持低热容量以实现最佳性能。大多数热探测器使用悬浮在空气中的薄膜红外吸收器，其下方有一层用于提供机械稳定性的支撑层。然而，这种支撑层增加了热容量却对红外吸收率没有贡献，从而降低了热探测器的性能。在本文中，我们介绍了一种使用具有C形横截面的带凸缘纳米线的偏振无关纳米线阵列吸收器。这种C形设计提供了机械稳定性，无需支撑层。尽管通常已知纳米线阵列具有偏振特性，但所提出的带凸缘纳米线的独特结构使其能够实现偏振无关特性，从而产生与薄膜吸收器相似的高吸收率。我们使用光学电路模型从理论上分析了带凸缘纳米线的偏振无关特性，并使用时域有限差分（FDTD）模拟优化了带凸缘纳米线结构。最后，我们通过实验证明了带凸缘纳米线的偏振无关特性，并证实了它们与薄膜吸收器相当的高吸收率。
