Tamm phonon-polaritons triggered in hyperbolic material hexagonal boron nitride

Abstract

Tamm phonon polaritons (TPhPs) have been recently predicted and experimentally observed for the first time in silicon carbide (SiC) film, allowing for enhanced light–matter interactions and new opportunities for manipulating light at the micro- and nano-scale. Hyperbolic material hexagonal boron nitride (hBN), a two-dimensional Van der Waals crystal, also supports phonon polaritons. However, TPhPs in hBN have not been systematically studied yet. In this paper, we theoretically investigate TPhPs triggered in the structure based on one-dimensional photonic crystal (PC) and hyperbolic material hBN film. It is found that the structure PC/spacer/semi-infinite hBN film can form TPhPs in the Type-II hyperbolic band, but not in the Type-I hyperbolic band. This phenomenon of selective excitation is attributed to the negative permittivity of hBN in the plane, rather than its out-of-plane permittivity. Importantly, TPhPs are sensitive to the thickness of the spacer, which can be regulated flexibly by changing the thickness. In addition, the selective excitation of TPhPs for hyperbolic bands in the configuration of finite hBN/spacer/PC is demonstrated using the same approach. It can be found that the absorption can reach 0.9 at the wavelength of 7.23 μm regardless of transverse electric or transverse magnetic waves, and the observed resonance has high quality factor of 181. This work provides a theoretical basis for TPhPs based on hyperbolic materials and has potential applications in highly sensitive sensors and selective absorbers.