Based on a general beam-propagation model, we derive in the paraxial approximation the analytical expressions for the spatial transverse shift (TS) and the angular TS of a beam reflected from the air-chiral interface. The results show that the TSs are closely related to the propagation behaviors of the right-circularly polarized (RCP) and the left-circularly polarized (LCP) waves in the chiral medium. When the L(R)CP wave becomes evanescent, the left (right)-elliptically polarized incident beam suffers a smaller TS. When the L(R)CP wave propagates, the left (right)-elliptically polarized incident beam experiences a greater TS. When the total internal reflection happens, neither of the two elliptically polarized incident beams suffers TSs. TSs can be controlled not only by adjusting the central angle of incidence, but also by tailoring the permittivity, permeability, and chirality parameter of the chiral medium.

We propose a thermal rectification structure composed of InSb and graphene-coated 3C-SiC separated by a nanoscale vacuum gap. To obtain an obvious thermal rectification effect, the permittivities of these materials are all considered to be temperature-dependent. Numerical calculations based on fluctuation electrodynamics reveal that the introduction of graphene into the structure enhances significantly near-field radiative heat flux and thermal rectification efficiency owing to the strong coupling of surface plasmon-polaritons between InSb and graphene. In general, the rectification efficiency above 60% can be maintained for the vacuum gap less than 70 nm. The rectification efficiency exceeding 95% is realized for a vacuum gap of 10 nm and a chemical potential of 0.1 eV. Increasing the emitter’s temperature leads to the drastic increase of the rectification efficiency in a wider temperature range. A lower chemical potential seems more favorable to raising rapidly the rectification efficiency. The above results might be helpful in designing a thermal diode with higher efficiency and wider vacuum gap.

No abstract

No abstract

No abstract