$\mathrm{^{130}Te_2}$ spectroscopic reference for neutral Ti lines at 391 nm and 498 nm

Abstract

We report on the use of ditellurium ($\mathrm{^{130}Te_2}$) as a frequency reference for laser locking at 391 nm and 498 nm optical wavelengths, which are of interest in titanium (Ti) laser-cooling experiments. In the ultraviolet region near the optical wavelength of 391 nm, 36 previously unobserved transitions were found using laser absorption spectroscopy in a 256 GHz range. Based on the established molecular structure of $\mathrm{^{130}Te_2}$, we attribute these lines to the $\mathrm{0_u^+\rightarrow 0_g^+}$ subsystem of the $\mathrm{^3Σ_u^-\rightarrow\ ^3Σ_g^-}$ transition with possible vibrational transitions of $ν=(28,27,26,25,24)\rightarrow 0$ and $(27,26)\rightarrow 1$. We measure the frequencies of these lines, and also of lines near 498 nm wavelength, and subsequently stabilize lasers at wavelengths of 391 nm (and 498 nm) to $\sim$60 MHz ($\sim$50 MHz) wide resonances in $\mathrm{^{130}Te_2}$, near the optical-pumping (laser-cooling) transitions in $\mathrm{^{48}Ti}$. We observe robust laser frequency locks, with Allan deviations of $4.9\times 10^{-10}$ ($3.6\times 10^{-11}$) at 10 s of averaging time for the 391 nm (498 nm) wavelength lasers.