Origin of persistent hole burning of N - V centers in diamond

New satellite features and antiholes in the persistent hole-burning spectrum of N-V centers in diamond, as well as their dependences on applied electric fields and frequency within the inhomogeneous absorption line, are reported. These results, together with reassignments of spin states of this center, permit an understanding of the origin of the satellite holes as well as of possible mechanisms for the persistent hole-burning phenomenon itself. In addition we report narrow optical interference fringes in heterodyne-detected spectra of persistent spectral holes in the N-V defect center in diamond and discuss a recent suggestion for high-resolution Ramsey-fringe hole-burning spectroscopy of solids based on phase-separated fields.