Abstract: We report a new W-band Electron Paramagnetic Resonance (EPR) probe design based on Fabry-Perot cavity. In this probe, a Fabry-Perot cavity with open structure and large effective volume is utilized as a resonator. Corrugated waveguides are designed to realize the microwave signal transmission between the W-band microwave bridge and the Fabry-Perot cavity. The probe works in W-band, and the unloaded quality factor is1 542. We conducted a room-temperature continuous wave EPR experiment with Mn(II) in CaO powder after assembling the probe into a W-band EPR spectrometer. Our work shows that the Fabry-Perot cavity can be utilized as a high sensitivity W-band EPR probe. The results show that the modulation field frequency and amplitude are100 kHz and8.9 G, respectively, and the absolute spin sensitivity is estimated to be6.6×108spins/(G⋅Hz).

Key words: Electron paramagnetic resonance, Fabry-Perot cavity, Corrugated waveguide, Sensitivity