Terahertz Magneto Optical Polarization Modulation Spectroscopy

TL;DR

This paper introduces advanced terahertz spectroscopy techniques for precise, rapid measurement of the complex Faraday angle in systems with broken time-reversal symmetry, demonstrated using GaAs electron gas.

Contribution

It presents a novel combination of terahertz time domain spectroscopy and polarization modulation for high-sensitivity, broadband Faraday rotation measurements.

Findings

Achieved polarization modulation sensitivity below 1 mrad.

Demonstrated broadband rotation measurements with less than 5 mrad precision.

Validated techniques using GaAs two-dimensional electron gas in a magnetic field.

Abstract

We report the development of new terahertz techniques for rapidly measuring the complex Faraday angle in systems with broken time-reversal symmetry using the cyclotron resonance of a GaAs two-dimensional electron gas in a magnetic field as a system for demonstration of performance. We have made polarization modulation, high sensitivity (< 1 mrad) narrow band rotation measurements with a CW optically pumped molecular gas laser, and by combining the distinct advantages of terahertz (THz) time domain spectroscopy and polarization modulation techniques, we have demonstrated rapid broadband rotation measurements to < 5 mrad precision.