Enhancing far-field thermal emission with thermal extraction

Yu, Zongfu; Sergeant, Nicholas P.; Skauli, T.; Zhang, Gang; Wang, Hailiang; Fan, Shanhui

doi:10.1038/ncomms2765

Cited by 91 publications

(73 citation statements)

References 33 publications

(35 reference statements)

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“…The power emitted by a finite-size body with area A can be increased up to n 2 AσT 4 by placing the emitter in a medium of refractive index n. This is in full agreement with standard radiometry, as the radiance in a medium with refractive index n is given by n 2 I b ðT; ωÞ. This feature can be used to extract more energy from a finite-size body by using a solid immersion lens type of geometry as discussed in Refs, [56,57].…”

Section: Discussionmentioning

confidence: 58%

Light Emission by Nonequilibrium Bodies: Local Kirchhoff Law

et al. 2018

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The goal of this paper is to introduce a local form of Kirchhoff law to model light emission by nonequilibrium bodies. While absorption by a finite-size body is usually described using the absorption cross section, we introduce a local absorption rate per unit volume and also a local thermal emission rate per unit volume. Their equality is a local form of Kirchhoff law. We revisit the derivation of this equality and extend it to situations with subsystems in local thermodynamic equilibrium but not in equilibrium between them, such as hot electrons in a metal or electrons with different Fermi levels in the conduction band and in the valence band of a semiconductor. This form of Kirchhoff law can be used to model (i) thermal emission by nonisothermal finite-size bodies, (ii) thermal emission by bodies with carriers at different temperatures, and (iii) spontaneous emission by semiconductors under optical (photoluminescence) or electrical pumping (electroluminescence). Finally, we show that the reciprocity relation connecting light-emitting diodes and photovoltaic cells derived by Rau is a particular case of the local Kirchhoff law.

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Section: Discussionmentioning

confidence: 58%

Light Emission by Nonequilibrium Bodies: Local Kirchhoff Law

et al. 2018

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“…Due to the spectrally tunable slow-light principle, the effective refractive index of the super absorptive hyperbolic metafilm pattern is very large, particularly for mid-far IR wavelengths, which is not naturally available. Therefore, being able to create a high index super absorptive/emissive material for mid-far IR wavelengths will provide a technological foundation for a variety of thermal applications, including extraction of more thermal energy from a more compact thermal emitter49, miniaturizing the dimension and improving the performance of conventional heat-to-light converters, thermophotovoltaic cells and radiative coolers/heaters50. This absorption engineering will lead to the development of controllable, effective media, and improve our ability to manipulate light in man-made metasurfaces that do not exist in the natural world51.…”

Section: Resultsmentioning

confidence: 99%

Broadband absorption engineering of hyperbolic metafilm patterns

Song

Zeng

et al. 2014

Sci Rep

163

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Perfect absorbers are important optical/thermal components required by a variety of applications, including photon/thermal-harvesting, thermal energy recycling, and vacuum heat liberation. While there is great interest in achieving highly absorptive materials exhibiting large broadband absorption using optically thick, micro-structured materials, it is still challenging to realize ultra-compact subwavelength absorber for on-chip optical/thermal energy applications. Here we report the experimental realization of an on-chip broadband super absorber structure based on hyperbolic metamaterial waveguide taper array with strong and tunable absorption profile from near-infrared to mid-infrared spectral region. The ability to efficiently produce broadband, highly confined and localized optical fields on a chip is expected to create new regimes of optical/thermal physics, which holds promise for impacting a broad range of energy technologies ranging from photovoltaics, to thin-film thermal absorbers/emitters, to optical-chemical energy harvesting.

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“…Recently, a number of works have demonstrated that near-field radiative heat transfer is enhanced by many orders of magnitude compared to the far-field limit for closely spaced objects with either natural 10,11 or engineered resonant surface modes [12][13][14][15][16] . There have also been efforts to couple these near-field modes into the far-field with the use of grating structures 17 , antennas 18 , and a thermal extraction lens 19,20 .…”

mentioning

confidence: 99%

Active thermal extraction of near-field thermal radiation

2016

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Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. Our study demonstrates a new approach to manipulate thermal radiation that could find applications in thermal management.

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Enhancing far-field thermal emission with thermal extraction

Cited by 91 publications

References 33 publications

Light Emission by Nonequilibrium Bodies: Local Kirchhoff Law

Light Emission by Nonequilibrium Bodies: Local Kirchhoff Law

Broadband absorption engineering of hyperbolic metafilm patterns

Active thermal extraction of near-field thermal radiation

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