Enhanced radiative heat transfer between nanostructured gold plates

Abstract

We compute the radiative heat transfer between nanostructured gold plates in the framework of the scattering theory. We predict an enhancement of the heat transfer as we increase the depth of the corrugations while keeping the distance of closest approach fixed. We interpret this effect in terms of the evolution of plasmonic and guided modes as a function of the grating's geometry. PACS numbers: 64.70.Nd, 44.40.+a, 44.05.+e The far-field radiative heat transfer between good conductive metals is very low at room temperature, since they are very good reflectors at the infrared frequencies of blackbody radiation. The radiative heat transfer is enhanced in the near field, due to the contribution of evanescent surface modes [1][2][3]. Polar materials like SiO 2 or SiC are in addition favored by the contribution of surface phonon polaritons whose resonance frequencies lie in the infrared [4]. There is an analogous effect for metals arising from the surface plasmons resonances but those lie in the ultraviolet and do not contribute significantly to the heat transfer [5].It has been shown recently that the radiative heat transfer can be controlled by nanostructuring the interfaces periodically. When the period d is much smaller than the wavelength λ and the separation distance L, the system can be treated using an effective refractive index for the equivalent homogeneous medium. It has been shown that the induced anisotropy introduces additional modes [6] and also allows modulating the flux [7]. For periods on the order of the wavelength, a full solution of Maxwell equations is needed. The heat transfer between two periodic slabs has been studied within a two dimensional approximation and for p-polarization using a finite difference time domain (FDTD) technique [8]. A flux enhancement attributed to the excitation of the structure's modes was found. While FDTD allows modeling complex shapes easily, dealing with bulk 3D media and accounting for polarization effects has not been achieved so far.In this letter, we compute the radiative heat transfer between 1D gold lamellar gratings in the framework of the scattering theory. We do include all propagation directions (the so-called conical diffraction) and all polarization states, which is of critical importance in order to deal quantitatively with cross-polarization effects [9]. The scattering theory is the most successful technique for treating the Casimir effect between bodies at thermodynamic equilibrium [10,11]. The method determines the electromagnetic field in the space between the two bodies in interaction in order to compute the Maxwell stress tensor in terms of the reflection amplitudes on the two bodies. When the two bodies are not at the same temperature, there is a net flux of energy transferred from the warm body to the cold one. Recently, this heat transfer problem between two bodies kept at different temperatures has also been formulated in terms of the scattering properties of the bodies [12][13][14][15].In the following, we use the scattering amplitudes wh...

Trace formulas for nonequilibrium Casimir interactions, heat radiation, and heat transfer for arbitrary objects

“…(See also Refs. [46][47][48][49][50][51][52][53][54] for recent studies of various aspects of heat transfer. )…”

Fluctuating-surface-current formulation of radiative heat transfer for arbitrary geometries

“…In this letter, we propose a novel formulation of radiative heat transfer for arbitrary geometries that is based on the fluctuating surface-current (FSC) method of classical EM fields [9]. Unlike previous scattering formulations based on basis expansions of the field unknowns best suited to special [10][11][12][13][14] or non-interleaved periodic [15] geometries, or formulations based on expensive, brute-force time-domain simulations [16], this approach allows direct application of the boundary element method (BEM): a mature and sophisticated surface-integral equation (SIE) formulation of the scattering problem in which the EM fields are determined by the solution of an algebraic equation involving a smaller set of surface unknowns (fictitious surface currents in the surfaces of the objects [17]). In what follows, we briefly review the SIE method, derive an FSC equation for the heat transfer between two bodies, and demonstrate its correctness by checking it against (as well as extending) previous results for spheres and cylinders.…”

Tunable narrow-band near-field thermal emitters based on resonant metamaterials

“…Therefore, highly efficient numerical methods are required to simulate the thermal radiation of arbitrary geometries. Some representative numerical methods for directly calculating thermal radiation are listed as follows: the scattering matrix method based on the rigorous coupled-wave analysis (RCWA) for periodic structures where the geometries are decomposed into multi-layers 36,37 ; the Fluctuating Surface Current (FSC) method using boundary element method where the geometric boundaries are decomposed into surface elements 38,39 ; the Monte-Carlo method by sampling thermally induced random currents 40 ; the Thermal Discrete Dipole Approximation (T-DDA) method 41,42 ; the NF-RT-FDTD method 43 which is a direct and non-stochastic algorithm accounting for the statistical nature of thermal radiation; and the Fluctuating Volume Current (FVC) method 44 . The WCE method that we used in this paper is developed to calculate thermal radiation of arbitrary geometries by expanding thermally induced random currents onto deterministic orthonormal current modes 29,45,46 .…”