This work addressed the estimate of the directional emissivity in the mid-infrared (MIR) channel around 4.0 microm from MODIS data. A series of bidirectional reflectances in MODIS channel 22 (3.97 mum) were retrieved using the method developed by Tang and Li (Int. J. Remote Sens. 29, 4907, 2008) and then were used to estimate the directional emissivity in this channel with the aid of the BRDF model modified by Jiang and Li (Opt. Express 16, 19310, 2008). To validate the estimated directional emissivity, a cross-comparison of MODIS derived emissivities in channel 22 using the proposed method were performed with those provided by the MODIS land surface temperature/emissivity product MYD11B1 data. The results show that the proposed method for estimating the directional emissivity in MIR channel gives results comparable to those of MYD11B1 product with a Mean Error of -0.007 and a Root Mean Square Error of 0.024.
Manipulating the thermal emission in the infrared (IR) range significantly impacts both fundamental scientific research and various technological applications, including IR thermal camouflage, information encryption, and radiative cooling. While prior research has put forth numerous materials and structures for these objectives, the significant challenge lies in attaining spatially resolved and dynamically multilevel control over their thermal emissions. In this study, a one-step ultrafast laser writing technique is experimentally demonstrated to achieve position-selective control over thermal emission based on the phase-change material GeSbTe (GST).
Nonreciprocal thermal radiation can differ in emissivity at specific angles, challenging traditional Kirchhoff's law, and creating opportunities for thermal emitters that don’t rely on magnetic fields.
The proposed mid-infrared thermal emitter operates between 12 μm to 20 μm with a wide angular range of 16° to 88°, utilizing a multilayered structure of Weyl semimetals and dielectrics.
This innovation optimizes emissivity across various angles and wavelengths, indicating potential applications in areas like radiative cooling, medical sensing, and energy conversion.
Blackbody radiation is incoherent and omnidirectional, whereas various novel applications in renewable energy require a degree of directional control of a thermally emitted beam. So far, such directional control has required nano-structuring the surface of a thermally emitting material, typically by forming diffraction gratings. This, however, necessitates lithography and usually results in polarization-dependent properties.
GPL Photonics Laboratory, State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
Directional control of thermal emission over its broad wavelength range is a fundamental challenge. Gradient epsilon-near-zero (ENZ) material supporting Berreman mode has been proposed as a promising approach. However, the bandwidth is still inherently limited due to the availability of ENZ materials covering a broad bandwidth and additional undesired omnidirectional modes in multilayer stacking with increased thickness.
Windows constitute a significant portion of the facade in buildings and modern ground transportation vehicles, such as commercial skyscrapers, high-speed trains, and subway systems. Traditional glass windows lack adequate thermal insulation and heat retention capabilities; Low-Emissivity (Low-E) glass can block external infrared radiation, it also impedes mobile communication signals, particularly those in the 5G Sub6G frequency band. This paper introduces an innovative metasurface glass designed to enhance 5G mobile communication signals within the interior of glass windows.
