Second Harmonic Generation Spectroscopy of Inversion Symmetry Breaking Weyl Semimetals

Weyl semimetals with acentric point groups permit bulk second order nonlinear optical processes by the very nature of their broken inversion symmetry. A common example of such an effect is second harmonic generation, in which two photons of frequency ω combine to produce a photon of frequency 2ω in a manner dependent not only on the symmetry of the crystalline lattice, but also on the electronic states involved in the optical transitions at these frequencies. Here, we present a spectroscopic second harmonic generation study of a Weyl semimetal, and discuss data taken as a function of incident and emitted polarization angle over a range of incident frequencies from the visible to the infrared.