Abstract: A process for the vapor phase deposition of a fluoride containing glass on a substrate, the said fluoride containing glass containing in mole percent with a total of 100%, 30-50 PbF.sub.2, 30-50 GaF.sub.3, 0-30 ZnF.sub.2, 1-5 MF.sub.2 wherein M is Mn or Cd, 1-5 InF.sub.3, 0-10 AlF.sub.3 and 0-10 adjuvant, which involves contacting the substrate with vapors emanating from a molten bath of metallic fluorides comprising a reception bath containing in mole percent with a total of 100%, 9-26 YF.sub.3, 19-38 BaF.sub.2, 35-40 InF.sub.3, 18-25 M'Fe.sub.2 wherein M' is Mn, Cal or Zn and 0-10 adjuvant to which reception bath has been added a sufficient amount of a mixture of PbF.sub.2, GaF.sub.3 and optionally AlF.sub.3. The invention also concerns a vitreous composition deposited on a substrate, thus obtained, which is useful as a waveguide in the infrared.