Impact of Nitrogen-Vacancy Color Centers on the Optical Kerr Effect in Diamond: A Femtosecond Z-Scan Study

TL;DR

This study investigates how nitrogen-vacancy centers affect the optical Kerr effect in diamond using femtosecond Z-scan measurements, revealing anisotropic nonlinear responses influenced by NV concentration.

Contribution

It provides new insights into the impact of NV centers on diamond's nonlinear optical properties, highlighting anisotropy and the negative contribution of NVs modeled as two-level systems.

Findings

Nonlinear refractive index shows four-fold rotational symmetry.

NV concentration reduces the amplitude of the nonlinear response.

NV centers contribute negatively to the nonlinear susceptibility.

Abstract

This study explores nonlinear optical effects in diamond crystals doped with nitrogen-vacancy (NV) centers, focusing on the optical Kerr effect in the infrared spectral region. By employing the Z-scan technique with 230 fs laser pulses at a wavelength of 1032~nm, we investigate the nonlinear refractive index of high-purity and NV-containing diamond crystals at NV concentrations of 0.3 ppm and 4.5 ppm. The results demonstrate a pronounced anisotropy in the nonlinear refractive index, which exhibits a four-fold rotational symmetry, with its amplitude reduced by the NV concentration. The reduction in non-linear susceptibility is linked to the negative contribution of NV centers, modeled as two-level systems upon a strong, laser field, red-detuned relative to their resonance frequency. These findings provide new insights into the interplay between NV centers and nonlinear optical properties of diamond, offering potential pathways for tunable nonlinear optics applications.