We have investigated the optical properties of quantum wire arrays grown on vicinal surfaces with lateral period of 180 Angstrom. Due to the specificity of the CdTe, for which the preferential orientations of step edges during the growth are along the (100) direction, vicinal substrates misoriented around the (LOO) direction are used. The 1D periodic potential modulation in CdTe/CdMnTe tilted superlattice is evidenced experimentally by the energy redshift of the photoluminescence observed when the superlattice is vertical. Such a behavior of the ground state in the 1D structure is accounted quantitatively by a theoretical approach which uses a sinusoidal modulation potential to describe the lateral confinement,