A wide bandwidth tunable optical low-frequency shifter is presented in this work. It is based on two acousto-optic devices operating in tandem. The relevant parameters of the specific configurations of acousto-optic interactions in paratellurite material are detailed. Results from numerical computations leading to the practical design parameters are given. The low-frequency shifter has been experimentally tested at a visible wavelength λ0=514 nm and a high efficiency (>60%) has been measured. The tuning capability of the optical shifter covers a bandwidth Δf=26 MHz.