Multiphoton-Excited Fluorescence of Silicon-Vacancy Color Centers in Diamond
Abstract
Silicon-vacancy color centers in nanodiamonds are promising as fluorescent labels for biological
applications, with a narrow, non-bleaching emission line at 738 nm. Two-photon excitation of this
fluorescence offers the possibility of low-background detection at significant tissue depth with high
three-dimensional spatial resolution. We have measured the two-photon fluorescence cross section
of a negatively-charged silicon vacancy (SiV^− ) in ion-implanted bulk diamond to be 0.74(19) ×
10^{−50} cm^4 s/photon at an excitation wavelength of 1040 nm. In comparison to the diamond nitrogen
vacancy (NV) center, the expected detection threshold of a two-photon excited SiV center is more
than an order of magnitude lower, largely due to its much narrower linewidth. We also present
measurements of two- and three-photon-excited SiV fluorescence spectra, finding an increase in the
two-photon cross section with decreasing wavelength.
Research Areas
