Terahertz magneto-optical response of bismuth-gadolinium-substituted rare-earth garnet film

We report the magneto-optical Faraday response of bismuth-gadolinium-substituted rare-earth iron garnet at terahertz frequencies ranging from 100 GHz to 1.2 THz. The maximum transmittance of +/- 45 degrees component is about 60% near the frequency point of 0.63 THz. When the external magnetic field change from -100 mT to +100 mT, the Faraday rotation angle is between -6 degrees and +7.5 degrees. The overall change of ellipticity is relatively small. The maximum value of the Verdet constant is about 260 degrees/mm/T at 0.1 THz and then gradually decreases to 80 degrees/mm/T at 1.2 THz. Within the considered frequency range, the thick film exhibits magnetically tunable, non-reciprocal characters and a strong magneto-optical effect within a small external magnetic field at room temperature, which will be widely used for the terahertz isolators, circulators, nonreciprocal phase shifters, and magneto-optical modulators. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The magneto-optical Faraday response of bismuth-gadolinium-substituted rare-earth iron garnet at terahertz frequencies showed high transmittance and Faraday rotation angle at certain frequencies, with magnetically tunable, non-reciprocal properties that can be used for terahertz devices.