Imaging of microwave field distribution over a non-fed gold pattern by using NV centers in diamond

Nitrogen-vacancy (NV) centers in diamond have been widely used as platforms for quantum information, magnetometry and imaging of microwave (MW) fields. High-precision spatial control of the MW field necessary to drive the electronic spin of NV centers is essential for these applications. Here, we report a controlled MW field distribution by excitation of a micrometer-scale gold pattern in vicinity of the diamond surface. The gold pattern excited by a planar ring MW antenna, acts as a receiving antenna and redistribute the MW field in a localized area, without a direct feed of electrical current. The planar ring MW antenna is designed to generate a uniform MW field on diamond substrate in an area of 0.785 mm², providing a useful tool for detecting the MW variations. We performed the imaging of the localized MW intensity on the micrometer-scale gold pattern by direct observation of electron spin Rabi oscillations, showing also the potential application of NV centers for imaging MW field and characterization of MW devices. We achieved an enhancement of about 19 times for the Rabi frequency on a scale of few micrometers for the gold pattern, compared to the bulk Rabi frequency in presence of the single planar ring MW antenna. Compared to previous methods, our method has been shown as a fast and easy tool for the spatial control of MW fields and spin manipulation of NV centers in diamond.