Open AccessOptical Kerr effect and third harmonic generation in topological Dirac/Weyl semimetal
Author(s) -
Tianning Zhang,
Kelvin J. A. Ooi,
Wenchao Chen,
L. K. Ang,
Yee Sin Ang
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.038270
Subject(s) - graphene , dirac fermion , physics , massless particle , dirac (video compression format) , terahertz radiation , semimetal , quasiparticle , weyl semimetal , condensed matter physics , quantum mechanics , topology (electrical circuits) , band gap , superconductivity , mathematics , combinatorics , neutrino
We study the nonlinear optical response generated by the massless Dirac quasiparticles residing around the topologically-protected Dirac/Weyl nodal points in three-dimensional (3D) topological semimetals. Analytical expressions of third-order interband nonlinear optical conductivities are obtained based on a quantum mechanical formalism which couples 3D Dirac fermions with multiple photons. Our results reveal that the massless Dirac fermions in three dimensions retains strong optical nonlinearity in terahertz frequency regime similar to the case of the two-dimensional Dirac fermions in graphene. At room temperature, the Kerr nonlinear refractive index and the harmonic generation susceptibility are found to be n 2 = 10 -11 ∼ 10 -8 m 2 W -1 and χ (3) = 10 -14 ∼ 10 -8 m 2 V -2 , respectively, in the few terahertz frequency regimes, which is comparable to graphene and orders of magnitudes stronger than many nonlinear crystals. Importantly, because 3D topological Dirac/Weyl semimetals possess bulk structural advantage not found in the strictly two-dimensional graphene, greater design flexibility and improved ease-of-fabrication in terms of photonic and optoelectronic device applications can be achieved. Our finding reveals the potential of 3D topological semimetals as a viable alternative to graphene for nonlinear optics applications.