Nonlinear plasmonics of three-dimensional Dirac semimetals

Abstract

The three-dimensional Dirac semimetal (3D DSM) is a new class of material with a slew of electronic and optical properties in common with graphene, while structurally having a bulk form like real metals. In particular, the Dirac band structure of 3D DSM conferred very high optical nonlinearities much like the case for graphene. Consequently, we found that 3D DSM has respectable nonlinear plasmonic performance in comparison with graphene, while retaining the structural benefits of bulk metals, having reduced passive plasmonic losses, and is much easier to handle in fabrication facilities. 3D DSM is expected to play a strong role in providing strong optical nonlinearities for all-optical switching and at the same time offering a superior platform for nanophotonic device integration.

Efficient generation of extreme terahertz harmonics in 3D Dirac semimetals

“…It is noteworthy that that the first-and third-order conductivities of 3D DSMs extracted from Eq. (3) agree with known results [15,39]. At the same time, we note that the full, non-perturbative response of 3D DSMs has never been presented until now in equations (3) and (4).…”

“…Here, we show that the recently discovered class of 3D Dirac semimetal (DSM) materials is a promising candidate for solid-state THz HHG, achieving high efficiencies with input field intensities on the order of 10 MW/cm 2 , more than 10 5 times weaker than required for conventional THz HHG. This applies not only to the generation of lower-order harmonics [13][14][15][16][17], but also to the generation of extreme harmonics, up to the 31 st order and beyond. In particular, by considering a Cd 3 As 2 thin film of 250 nm thickness (readily obtained using methods like molecular beam epitaxy [14,16,[18][19][20][21][22]), we predict that conversion efficiencies exceeding 10 −5 can be achieved as high as the 31 st harmonic.…”

Highly efficient terahertz generation using 3D Dirac semimetals

“…For this reason, the 3D DSM Cd 3 As 2 , 13 which possesses exceptionally high Fermi velocities and electron mobilities, 12,13 has been used to generate highly efficient terahertz high-order harmonics from input terahertz pulses, [14][15][16][17] and studied as a platform for nonlinear plasmonics. 18,19 Related materials like Weyl semimetals have been shown to support chiral terahertz emission and polarization manipulation. 20 We show that the extreme optical nonlinearity of 3D DSMs can be leveraged for highly efficient optical-to-terahertz conversion over nanometer-scale propagation distances.…”

Control and Optimization of High Harmonic Generation in 3D Dirac Semimetals

“…Threedimensional Dirac semimetals (3D DSMs) [13][14][15][16][17][18], whose massless charge carriers result in extreme nonlinearity in the THz regime, is one such example. Recent experiments [19,20] and theory [21][22][23][24] have verified the promise of 3D DSMs in realizing compact, highly efficient THz HHG sources. In particular, even for moderate driving fields of ≤10 MV/m, highly efficient generation of the 3rd [19] and up to the 7th [20] harmonic have been demonstrated using the 3D DSM Cd 3 As 2 , with a theoretical study predicting efficient HHG up to the 31st order [23].…”