Broadband loop gap resonator for nitrogen vacancy centers in diamond
Author(s)Eisenach, ER; Barry, JF; Pham, LM; Rojas, RG; Englund, DR; Braje, DA; ... Show more Show less
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© 2018 Author(s). We present an S-band tunable loop gap resonator (LGR), which provides strong, homogeneous, and directionally uniform broadband microwave (MW) drive for nitrogen-vacancy (NV) ensembles. With 42 dBm of input power, the composite device provides drive field amplitudes approaching 5 G over a circular area ≈50 mm2 or cylindrical volume ≈250 mm3. The wide 80 MHz device bandwidth allows driving all NV Zeeman resonances for bias magnetic fields below 20 G. The device realizes percent-scale MW drive inhomogeneity; we measure a fractional root-mean-square inhomogeneity σrms = 1.6% and a peak-to-peak variation σpp = 3% over a circular area of 11 mm2 and σrms = 3.2% and σpp = 10.5% over a larger 32 mm2 circular area. We demonstrate incident MW power coupling to the LGR using two methodologies: a printed circuit board-fabricated exciter antenna for deployed compact bulk sensors and an inductive coupling coil suitable for microscope-style imaging. The inductive coupling coil allows for approximately 2π steradian combined optical access above and below the device, ideal for envisioned and existing NV imaging and bulk sensing applications.
Review of Scientific Instruments