Observation of Coherent Population Oscillations in NV Centers in Diamond in the Microwave Spectral Range

We report the results of experiments on observation of specific features in the spectrum of optically detected magnetic resonance in ensembles of NV centers in diamond at room temperature upon excitation of low-frequency transitions by dual-frequency and amplitude-modulated single frequency microwave radiation. The dependence of parameters of these specific features on intensity of optical radiation and power of microwave radiation is investigated.