Effects of laser-induced heating on nitrogen-vacancy centers and single-nitrogen defects in diamond

We investigate the effects of laser-induced heating of NV-and P1 defects in diamonds by X-band CW EPR spectroscopy, with particular attention to temperature effects on the zero field splitting and electron polarization. A 532 nm laser with intensities of 7-36 mW mm(-2) is sufficient to heat diamond samples from room temperature to 313-372 K in our experimental setup. The temperature effects on the determined NV-zero-field splittings are consistent with previously observed non-optical heating experiments. Electron spin polarization of the NV-defects were observed to increase, then saturate, with increasing laser light intensities up to 36 mW mm-2 after accounting for heating effects. We observe that EPR signal intensities from P1 centers do not follow a Boltzmann trend with laser-induced sample heating. These findings have bearing on the design of diamond-based polarization devices and magnetometry applications.