分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Kirchhoff s law is one of the most fundamental law in thermal radiation. The violation of traditional Kirchhoff s law provides opportunities for higher energy conversion efficiency. Various micro-structures have been proposed to realize single-band nonreciprocal thermal emitters. However, dual-band nonreciprocal thermal emitters remain barely investigated. In this paper, we introduce magneto-optical material into a cascading one-dimensional (1-D) magnetophotonic crystal (MPC) heterostructure composed of two 1-D MPCs and a metal layer. Assisted by the nonreciprocity of the magneto-optical material and the coupling effect of two optical Tamm states (OTSs), a dual-band nonreciprocal lithography-free thermal emitter is achieved. The emitter exhibits strong dual-band nonreciprocal radiation at the wavelengths of 15.337 um and 15.731 um when the external magnetic field is 3 T and the angle of incidence is 56 degree. Besides, the magnetic field distribution is also calculated to confirm that the dual-band nonreciprocal radiation originates from the coupling effect between two OTSs. Our work may pave the way for constructing dual-band and multi-band nonreciprocal thermal emitters.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Over the last few years, broken symmetry within crystals has attracted extensive attention since it can improve the control of light propagation. In particular, low-symmetry Bravais crystal can support shear polaritons which has great potential in thermal photonics. In this work, we report a twist-induced near-field thermal control system based on the low-symmetry Bravais crystal medium (\b{eta}-Ga2O3). The near-field thermal radiation (NFTR) between such crystal slabs is nearly four orders of magnitude larger than the blackbody limit, exceeding the NFTR from other traditional dielectric materials. Moreover, we show that this crystal can serve as an excellent platform for twist-induced near-field thermal control. Due to the intrinsic shear effect, the twist-induced modulation supported by low-symmetry Bravais crystal exceeds that by high-symmetry crystal. We further clarify how the shear effect affects the twist-induced thermal-radiation modulation supported by hyperbolic and elliptical polaritons and show that the shear effect significantly enhances the twist-induced thermal control induced by the elliptical polariton mode. These results open new directions for thermal-radiation control in low-symmetry materials, including geological minerals, common oxides, and organic crystals.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Near-field radiative heat transfer (NFRHT) has received growing attention because of its high intensity far beyond the Planck's black-body limit. Insertion of a third object in proximity of the two particles can significantly influence and manipulate its NFRHT. However, for the system composed of many particles, effect of the many-body interaction (MBI) on the NFRHT between arbitrary two particles of interest caused by the neighboring particles lying in proximity is still unclear (namely, 'proximate' MBI), which is the focus of this work. Three typical kinds of the proximate ensemble: one-dimensional particle chain, two-dimensional square-lattice particle plane and particle grating, are considered by using the many-body radiative heat transfer theory. When increasing the proximate particle size, the effect of many-body interaction on NFRHT will experience a radical change from inhibition to enhancement. It is worth mentioning that the unique enhancement on NFRHT caused by the proximate particle chain is different from the reported inhibition effect. The proximate particle polarizability increases when increasing the particle radius, which will affect the interaction between the proximate particles and the main particle (even when the main particle size does not change at all), and then results in enhancement of heat transfer between the main particles. As for the symmetry breaking effect on the NFRHT, when twisting the proximate particle ensemble, the proximate MBI accounts for a smooth and non-oscillated twisting angle dependence of NFRHT, different from the oscillation phenomenon of NFRHT for particle gratings mediated by the intra-ensemble and inter-ensemble MBI. This work will deepen the understanding of the NFRHT in dense particulate systems and guide applications for thermal management in micro-/nano-electromechanical devices.
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