A metamaterial frequency-selective super-absorber that has absorbing cross section significantly bigger than the geometric cross section

Overcoming the acoustic diffraction limit in photoacoustic imaging by localization of flowing absorbers

The resolution of photoacoustic imaging deep inside scattering media is limited by the acoustic diffraction limit. In this work, taking inspiration from super-resolution imaging techniques developed to beat the optical diffraction limit, we demonstrate that the localization of individual optical absorbers can provide super-resolution photoacoustic imaging well beyond the acoustic diffraction limit. As a proof-of-principle experiment, photoacoustic cross-sectional images of microfluidic channels were obtained with a 15 MHz linear CMUT array while absorbing beads were flown through the channels.…

采用光谱定制的碳纳米管膜实现具有Dallenbach型双层结构的宽带太阳能选择性吸收器

Broadband Solar Selective Absorber with Dallenbach-type Bilayer Structure Achieved Using Carbon Nanotube Membranes with Tailored Optical Spectra

针对传统材料限制干涉型吸收器制备的问题，本研究采用光谱定制的超薄单壁碳纳米管膜作为吸收层，制备Dallenbach型双层结构太阳能吸收器，实现高选择性吸收与低辐射损失，性能优于类黑体吸收器。

超越 Rozanov 判据的线性时不变薄吸波体求和规则界限

Sum Rule Bounds Beyond Rozanov Criterion in Linear and Time-Invariant Thin Absorbers

本文揭示了 Rozanov 推导中的隐藏假设，提出了适用于 LTI 层吸波体的新求和规则以放宽吸收极限约束，并通过用可穿透阻抗片替代 PEC 边界，设计了超越 Rozanov 界限的实用 LTI 薄吸波层。

Modeling electron dynamics coupled to continuum states in finite volumes

Absorbing boundaries are frequently employed in real-time propagation of the Schrödinger equation to remove spurious reflections and efficiently emulate outgoing boundary conditions. These conditions are a fundamental ingredient for an implicit description of observables involving infinitely extended continuum states. In the literature, several boundary absorbers have been proposed. They mostly fall into three main families: mask function absorbers, complex absorbing potentials, and exterior complex-scaled potentials. To date none of the proposed absorbers is perfect, and all present a certain…

Broadband reflectionless metasheets: Frequency-selective transmission and perfect absorption

Energy of propagating electromagnetic waves can be fully absorbed in a thin lossy layer, but only in a narrow frequency band, as follows from the causality principle. On the other hand, it appears that there are no fundamental limitations on broadband matching of thin absorbing layers. However, known thin absorbers produce significant reflections outside of the resonant absorption band. In this paper we explore possibilities to realize a thin absorbing layer which produces no reflected waves in a very wide frequency range, while the transmission coefficient has a narrow peak of full absorption…

平面薄膜在极限厚度下的完美吸收

Perfect Absorption at the Ultimate Thickness Limit in Planar Films

该研究理论探究平面薄膜完美吸收的厚度极限，提出拓扑保护完美吸收的设计框架，推导厚度与介电损耗的关系，为超灵敏光吸收体设计提供指导。

使用频域连续波太赫兹光谱对毫米波吸收体的反射率测量

Reflectance measurements of mm-wave absorbers using frequency-domain continuous wave THz spectroscopy

本文搭建了频域连续波太赫兹光谱测试平台，在100-500 GHz范围内系统测量了五种毫米波吸收体的反射特性，为CMB实验的光学负载抑制提供关键数据支持。

Relativistic frequency shifts in a rotating waveguide

A photon source is located in a rotating waveguide. An absorber with a sharp absorbing frequency absorbs some of the emitted photons. This decreases the number of photons which are detected by a detector. The frequency (energy) spectrum measured in the absorber depends on the setup (the positions of the source and the detector), and this spectrum determines the amount of absorption. The shifts are calculated for different configurations. Among other things, it is seen that even if the source and the absorber are at rest (while the waveguide is rotating), there is a nonzero frequency shift.