Vortex beams of far-infrared synchrotron radiation for spectroscopy of quantum materials at MET, NSLS-II BNL

We present a design of an optics system for conversion between conventional circularly or linearly polarized coherent synchrotron radiation into a vortex beam with a non-zero orbital angular momentum (OAM). The modified optical setup will be operational in a broad-band spectral range from 20 cm$^{\mathrm{-1}}$ up to 4000 cm$^{\mathrm{-1}}$ using Si and ZnSe axicone retarders producing OAM with $l=+$/-1. Beams with higher order of the OAM $l=+$/-1, $+$/-2, $+$/-3, $+$/-4 and $+$/-5 will be achieved with a motorized phase-shifting spiral mirror. Quantum materials will be studied using vortex beams at the MET beamline of NSLS-II, Brookhaven National Lab at low temperatures and in strong magnetic fields. This work is supported by NJIT-SEED Grant.