Polarized Reflectivity of Weyl Semimetals in the Near- and Mid-Infrared using a Liquid Crystal Variable Retarder

We show that one can use a Liquid Crystal Variable Retarder to achieve complete control over the linear or circular polarization of light from a pulsed laser which ranges from 680 nm to 4000 nm (1.8 eV to 0.3 eV). It is thus possible to continuously tune the four relevant polarizations |x>, |y>, |σ+> and |σ-> over this entire energy range and so extract the polarized reflectivity from a number of materials. We show how to calibrate such a system and show as examples polarized reflectivity spectra for a number of Weyl semimetals.