Efficient microwave radiation using broadened-bandwidth coplanar waveguide resonator on assembly of nitrogen-vacancy centers in diamond

We demonstrate a coplanar waveguide resonator for efficiently coupling a microwave magnetic field into nitrogen-vacancy centers in diamond. The resonator has a resonant frequency of around 2.87 GHz with a bandwidth of 820 MHz, ensuring the eight dips characteristic of optically detected magnetic resonance (ODMR) are clearly observed and the normalized ODMR improves over that of a previous system under external magnetic fields up to 60 G. The stronger magnetic field distribution with a uniformity of 82% determines the result of the normalized ODMR and bandwidth of the ODMR signal being 1.75 times higher and 12.5% lower than that of the previous system with a copper ring.