  We study and demonstrate the frequency conversion of UV radiation, resonant
with 369.5 nm transition in Yb+ ions to the C-band wavelength 1580.3 nm and
vice-versa using a reverse proton-exchanged waveguide in periodically poled
lithium niobate. Our integrated device can interface trapped Yb+ ions with
telecom infrastructure for the realization of an Yb+ based quantum repeater
protocol and to efficiently distribute entanglement over long distances. We
analyse the single photon frequency conversion efficiency from the 369.525 nm
to the telecom wavelength and its dependence on pump power, device length and
temperature. The single-photon noise generated by spontaneous Raman scattering
of the pump is also measured. From this analysis we estimate a single photon
conversion efficiency of 9% is achievable with our technology with almost
complete suppression of the Raman noise.
