莫不是一种新的光在宇宙？自19世纪后期，科学家们已经认识到，当加热时，所有材料在发射波长的预测的光谱的光。研究今天出版 科学性报告 呈现的材料会发光，似乎当加热到超出上限由自然法设置。
In 1900, Max Planck first mathematically described a pattern of radiation and ushered in the quantum era with the assumption that energy can only exist in discrete values. Just as a fireplace poker glows red hot, increasing heat causes all materials to emit more intense radiation, with the peak of the emitted spectrum shifting to shorter wavelengths as heat rises. In keeping with Planck’s Law, nothing can emit more radiation than a hypothetical object that absorbs energy perfectly, a so-called “blackbody.”
The new material discovered by Shawn Yu Lin, lead author and a professor of physics at Rensselaer Polytechnic Institute, defies the limits of Planck’s law, emitting a coherent light similar to that produced by lasers or LEDs, but without the costly structure needed to produce the stimulated emission of those technologies. In addition to the spectroscopy study just published in 科学性报告林此前公布的影像学研究中 IEEE光子学杂志。无论是在1.7微米关于，哪个是电磁波谱的近红外部分示出了辐射的尖峰。
“These two papers offer the most convincing evidence of ‘super-Planckian’ radiation in the far-field,” said Lin. “This doesn’t violate Planck’s law. It’s a new way to generate thermal emission, a new underlying principle. This material, and the method that it represents, opens a new path to realize super-intense, tunable LED-like infrared emitters for thermophotovoltaics and efficient energy applications.”
For his research, Lin built a three-dimensional tungsten photonic crystal — a material that can control the properties of a photon — with six offset layers, in a configuration similar to a diamond crystal, and topped with an optical cavity that further refines the light. The photonic crystal shrinks the spectrum of light that is emitted from the material to a span of about 1 micrometer. The cavity continues to squeeze the energy into a span of roughly 0.07 micrometers.
In both the imaging and spectroscopy study, Lin prepared his sample and a blackbody control — a coating of vertically aligned nanotubes on top of the material — side by side on a single piece of silicon substrate, eliminating the possibility of changes between testing the sample and control that could compromise the results. In an experimental vacuum chamber, the sample and control were heated to 600 degrees Kelvin, about 620 degrees Fahrenheit.
The IEEE光子学杂志 用近红外常规电荷耦合器件拍摄纸张呈现的图像，照相机可以捕获该材料的预期的辐射发射。
Although theory does not fully explain the effect, Lin hypothesizes that the offsets between the layers of photonic crystal allow light to emerge from within the many spaces inside the crystal. The emitted light bounces back and forth within the confines of the crystal structure, which alters the property of the light as it travels to the surface to meet the optical cavity.
The new material could be used in applications like energy harvesting, military infrared-based object tracking and identification, producing high efficiency optical sources in the infrared driven by waste heat or local heaters, research requiring environmental and atmospheric and chemical spectroscopy in the infrared, and in optical physics as a laser-like thermal emitter.
“This exciting and unexpected discovery emphasizes the importance of conducting paradigm-shifting fundamental research that can move the boundaries of knowledge in physics and material science" said Curt Breneman, Dean of the Rensselaer School of Science. “We are very proud of Professor Lin and his team for leading the way towards the development of new and transformative technologies."
“An In-situ and Direct Confirmation of Super-Planckian Thermal Radiation Emitted From a Metallic Photonic-Crystal at Optical Wavelength” was supported by NSF under award ECCS-1840673-NOA (device characterization and modeling) and DOE Office of Science under award DE-FG02-06ER46347 (device fabrication). At Rensselaer, Lin was joined by Mei-Li Hsieh, B. Frey, James A. Bur, Xuanjie Wang, and Shankar Narayanan, as well as Sajeev John of the University of Toronto, and Ting-Shan Luk of Sandia National Laboratory.
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