We present a miniature two-port resonator with an Ω-shaped coplanar coil designed to excite optically detected magnetic resonance at 2.87 GHz in a diamond sample hosting nitrogen-vacancy (NV-centers). The resonator architecture was chosen because its fabrication does not require patterning planar structures on the diamond. The dimensions were calculated, and electromagnetic simulations using the finite-element method were performed to obtain the S-parameters both without and with the diamond included. After fabrication, the S-parameters were measured with a vector network analyzer. For the resonator with the diamond mounted on it, at 2.87 GHz we obtained a minimum reflection coefficient |S11| approx; −24.85 dB, a loaded quality factor QH approx; 44.2, and a −3 dB bandwidth of about 66 MHz.
Guseva et al. (Wed,) studied this question.