Design of a quantum-spin sensor with sub-micron resolution and enhanced optical read-out ability by the nitrogen-vacancy centers in diamond

To solve the inefficiency of optical out-coupling of the nitrogen-vacancy (NV) luminescence in bulk diamond, we propose a quantum-spin sensor based on the NV centers in diamond. The sensor is able to map out the microwave magnetic field or temperature and other distributions on a sub-micron scale. We demonstrate the implementation of a nanowire (NW) array fabricated from a regular diamond sensing layer and nano-antennas as photonic waveguides fabricated on the backside of a diamond substrate. By tuning the parameters, we used numerical modeling to find an optimal range of the NW’s parameters that allow for a large collection efficiency of the emitted photons. By systematic optimization, we have observed an optical read-out efficiency strengthened by a factor of ~ 30. Since the optimized parameters for the sensing device are in the order of hundreds of nanometers, the sensor can achieve an enhanced sensitivity with sub-micron resolution. Graphical abstract