Integrated microwave cavity and antenna to improve the sensitivity of diamond NV center spin-based sensors

An microwave-cavity antenna was designed to manipulate the spin state in diamond. It consists of an Ω antenna and a microwave cavity with the thickness of 0.35mm and Q-value of 65. The microwave intensity increased 12 times than that of the Ω antenna. The size of homogeneity area is 25πmm2 and the heterogeneity is less than 2.3%. Hence, more spin structures in large-sized diamonds with high concentration can be homogeneous excited. As applied in the spin-based magnetometer, the sensitivity increased 13 times, and noise reduced to 0.5nT/Hz1/2. It proves a way to develop the high sensitive spin-based sensors.