3D Dirac Semimetal Supported Tunable TE Modes

Abstract

The tunable propagation properties of transverse electric (TE) plasmonic modes have been investigated in the mid-IR spectral region by using air-Dirac semimetal (DSM)-Si asymmetric structures, including the effects of Fermi levels, temperatures, and scattering times. The results manifest that on the condition that the Fermi level of DSM layer is not very large (2|𝝁 c |<ℏ𝝎) and temperature is relatively high (about 100 K), the proposed DSM asymmetric structure supports obvious TE modes, which is quite different from the graphene symmetric structure limited to low liquid helium temperature. The transition frequency increases with Fermi level, the peak position of the real part and the saturation region of the imaginary part of effective index indicates an obvious blue shift. As temperature decreases, the contribution of interband transition becomes stronger, the 3D DSM indicates better dielectric properties and sustains stable TE mode. If scattering time is shorter than 0.1 ps, its effects on the propagation properties are very strong, resulting in a redshift of the real part of effective index. The results are very helpful to understand the tunable properties of DSM TE structures and aid the design of novel plasmonic devices, such as polarizers, modulators, and filters.

Two-Dimensional Plasmons in Laterally Confined 2D Electron Systems

“…The transverse-electric ( ) mode, which is determined with equation , exists only in systems with . For example, it takes place in narrow frequency range near the interband transitions frequencies in graphene [ 43 , 44 ] and other Dirac materials [ 45 , 46 ]. The solution of the second equation, , corresponds to the transverse-magnetic ( ) mode.…”

Recent advances in photonics of three-dimensional Dirac semimetal Cd3As2

“… – 121 It was discovered that when the Fermi level rises, the transition frequency of TE modes increases and the peak location of the real and imaginary portions of effective indices exhibit evident blue shifts. At low temperatures, the interband transition contributes more, and the 3D DSM layer exhibits improved dielectric characteristics and enables a stronger TE mode 122 …”

“…At low temperatures, the interband transition contributes more, and the 3D DSM layer exhibits improved dielectric characteristics and enables a stronger TE mode. 122 Plasmon-induced transparency (PIT) is a plasmon analogue of electromagnetically induced transparency. It is created by significant destructive interference between plasmon superradiation and plasmon subradiation modes.…”

Photoactive terahertz metasurfaces for ultrafast switchable sensing of colorectal cells

“…To realize multi-mode and active-operation of metasurfaces that are promising in communications and imaging, potential efforts have been devoted to designing reconfigurable devices by integrating active media, such as traditional semiconductors, [16][17][18][19][20][21][22][23][24] phase change materials, 25,26 liquid crystals, 27 perovskites 28,29 and Dirac semimetals. [30][31][32] Compared with other media, traditional semiconductors including silicon, germanium and gallium arsenide generally have better performance in practical scenarios, owing to mature fabrication techniques, cheap processing cost, and large modulation depth. [16][17][18][19][20][21][22][23][24] Depending on the intrinsic properties of active media, a series of external stimuli embracing optical, [16][17][18]20,21,23,24,26,27,33 electrical, 19,22,27 and thermal 25,26 methods have jointly promoted the evolution of active metasurfaces towards a more flexible and intelligent direction.…”