Lithium niobate (LN) films have been obtained on pure congruent single-domain LN substrates by the liquid phase epitaxy technique. Li-rich flux of LiVO$_3$ has been used. The optimum temperature for the film preparation has been found to be 860°C. Raman and photoluminescence microspectroscopy were used to analyse the Li/Nb ratio, which decreases along the film depth, and the vanadium concentration, which increases along the film depth.