Efficient wireless non-radiative mid-range energy transfer

A triple-mode mid-infrared modulator for all-surface radiative thermal management

Thermal management is ubiquitous in the modern world and indispensable for a sustainable future. Radiative heat management provides unique advantages because the heat transfer can be controlled by the surface. However, different surface emissivities require different tuning strategies. Here, we demonstrate a triple-mode mid-infrared modulator that can switch between passive heating and cooling suitable for all types of object surface emissivities. The device is composed of a surface-textured infrared-semi-transparent elastomer coated with a metallic back reflector, which is biaxially strained …

Radiative Carrier Lifetime in Ge$_{1-x}$Sn$_x$ Mid-Infrared Emitters

Ge$_{1-x}$Sn$_x$ semiconductors hold the premise for large-scale, monolithic mid-infrared photonics and optoelectronics. However, despite the successful demonstration of several Ge$_{1-x}$Sn$_x$-based photodetectors and emitters, key fundamental properties of this material system are yet to be fully explored and understood. In particular, little is known about the role of the material properties in controlling the recombination mechanisms and their consequences on the carrier lifetime. Evaluating the latter is in fact fraught with large uncertainties that are exacerbated by the difficulty to i…

Tuning Optical Properties of Metamaterials by Mie Scattering for Efficient Sub-ambient Daytime Radiative Cooling

The management of the abundant eggshell biowaste produced worldwide has become a problematic issue due to the generated odor and microorganisms after directly disposing eggshell biowaste in landfills. Herein, we propose a novel method to convert the hazardous eggshell biowaste to valuable resources for energy management applications. Eggshell-based films are fabricated by embedding eggshell powders into polymer matrix to achieve highly efficient sub-ambient daytime radiative cooling. Benefiting from the Mie scattering of eggshell particles/air pores in the solar spectrum and strong emission of…

Metamaterial-Enhanced Coupling between Magnetic Dipoles for Efficient Wireless Power Transfer

Non-radiative coupling between conductive coils is a candidate mechanism for wireless energy transfer applications. In this paper, we propose a power relay system based on a near-field metamaterial superlens, and present a thorough theoretical analysis of this system. We use time-harmonic circuit formalism to describe all interactions between two coils attached to external circuits and a slab of anisotropic medium with homogeneous permittivity and permeability. The fields of the coils are found in the point-dipole approximation using Sommerfeld integrals, which are reduced to standard special …

Frequency-stable robust wireless power transfer based on high-order pseudo-Hermitian physics

Non-radiative wireless power transfer (WPT) technology has made considerable progress with the application of the parity-time (PT) symmetry concept. In this letter, we extend the standard second-order PT-symmetric Hamiltonian to high-order symmetric tridiagonal pseudo-Hermitian Hamiltonian, relaxing the limitation of multi-source/multi-load system based on non-Hermitian physics. We proposed a three-mode pseudo-Hermitian dual-transmitter-single-receiver circuit and demonstrate that robust efficiency and stable frequency WPT can be achieved even though PT-symmetry is not satisfied as usual. In a…

由生物衍生陶瓷-聚合物涂层实现的被动白天辐射冷却

Passive Daytime Radiative Cooling Enabled by Bio-Derived Ceramic-Polymer Coatings on Rapid-Curing Fiberglass Casts

本研究提出了一种基于生物衍生陶瓷-聚合物涂层的被动白天辐射冷却系统，利用快速固化玻璃纤维铸模实现高效冷却，达到90%以上的太阳反射率和15摄氏度的降温效果。