Simultaneous measurement of circular dichroism and Faraday rotation at terahertz frequencies utilizing electric field sensitive detection via polarization modulation.

A far-infrared system measures the full complex Faraday angle, the rotation as well as the ellipticity, with an unprecedented accuracy of 10 microrad/T. The system operates on several far-infrared laser lines in the spectral range from 0.3 to 6 THz and produces results as a continuous function of temperature from 10 to 310 K and applied fields between +/-8 T. Performance of the instrument is demonstrated by measurements on a GaAs two-dimensional electron gas heterostructure and Bi(2)Sr(2)CaCu(2)O(8+x) single crystal.