Multifunctional asymmetric directional thermal radiation device and its detecting potential

Abstract

In this paper, a Weyl semimetal asymmetrical metastructure (WSAM) is proposed to fulfill multifunctional thermal radiation adjustment in the near-infrared band. When the transverse magnetic (TM) waves incident from two sides of the WSAM, two kinds of different thermal asymmetry have been established. From the forward direction, thermal radiation (e) displays a huge asymmetry degree (η_1,2 = |e(θ) - e(−θ)| = 0.9) for the positive and negative incident angles (±θ), which can be applied in the area of thermal management. At the same time, for TM waves incident with +θ, radiation peak (e > 0.9) corresponding to wavelength has a linear relationship with θ as λ = −5.09 × 10⁻⁴θ + 4.5221 μm, and the average values of introduced figure of merit, detection limit, and Q are 0.016 /°, 3.1958°, and 141.4229, respectively, all displays good detection of θ, which is the direction of transmitted TM waves. From the backward direction, asymmetric directional thermal radiation (ADTR) has been made. In the case of λ = 4.434 μm, ADTR covers the range of 34° ∼ 82°, and η₂ can get as 0.45, while at λ = 4.430 μm, the range of ADTR shortens to 51° ∼ 77.3°, which has a better directionality, and the η₂ improves to 0.75. In this situation, the designed WSAM has the potential for infrared stealth, infrared information encryption, and thermal radiation cooling.