Bright near-surface silicon vacancy centers in diamond fabricated by femtosecond laser ablation

We report the generation of single negatively charged silicon vacancy (SiV⁻) color centers by focusing a femtosecond (fs) laser on top of a high-purity diamond coated with a layer of Si nanoball. Under the interaction of a high-intensity fs laser, Si atoms were ionized and implanted into the diamond, accompanied with the creation of vacancies. After annealing at 850°C in vacuum for 1 h, the photoluminescence spectra of bright spots around the created crater presented a typical strong zero-phonon line at around 737 nm of SiV⁻ centers. Bright single SiV− color centers could be observed with a maximum saturating counting rate of 300 × 10³ counts∕s. We explain the formation mechanism of SiV⁻ centers in diamond via a Coulomb explosion model. The results demonstrate that fs laser ablation can be utilized as a very promising tool to conveniently fabricate single bright SiV⁻ centers in diamond.