Terahertz electron paramagnetic resonance spectroscopy using continuous-wave frequency-tunable photomixers based on photoconductive antennae

In this article, we demonstrate terahertz (THz) electron paramagnetic resonance (EPR) spectroscopy using a frequency-tunable photomixing source/detection system to investigate the electronic structure of solid-state samples in a microscopic manner. Fiber-coupled photoconductive antennae were used to generate and detect continuous THz waves obtained as the beat signals from two laser beams with different wavelengths. We will show some examples of EPR spectroscopy obtained by multi-frequency EPR measurements at room temperature. The technique reported here has several advantages, including high spectral resolution, wide frequency-range operation, high dynamic range, owing to the continuous-wave (cw) and tunable generation/detection of THz waves.