Multiple-photon excitation of nitrogen vacancy centers in diamond

Abstract

We report the observation of multiphoton photoluminescence excitation (PLE) below the resonant energies of nitrogen vacancy (NV) centers in diamond. The quadratic and cubic dependence of the integrated fluorescence intensity as a function of excitation power indicates a two-photon excitation pathway for the ${\mathrm{NV}}^{\ensuremath{-}}$ charge state and a three-photon process involved for the neutral ${\mathrm{NV}}^{0}$ charge state, respectively. Comparing the total multiphoton energy with its single-photon equivalent, the PLE spectra follows the absorption spectrum of single photon excitation. We also observed that the efficiency of photoluminescence for different charge states, as well as the decay time constant, was dependent on the excitation wavelength and power.