Temperature-dependent second-harmonic generation from color centers in diamond

Under infrared ultrashort pulse laser stimulation, we investigated temperature-dependent second-harmonic generation (SHG) from nitrogen-vacancy (NV)-introduced bulk diamond. The SHG intensity decreases in the temperature range of 20-300 $^{\circ}C$, due to phase mismatching caused by refractive index modification. We discovered that optical phonon scattering outperforms acoustic phonon one in NV diamond by fitting the temperature dependence of SHG intensity using a model based on the bandgap change via the deformation potential interaction. This study presents an efficient and viable way for creating diamond-based nonlinear optical temperature sensing.