A local nanocrystalline formation in a Neodymium-Ytterbium codoped oxyfluoride glass has been obtained. It has been studied the intense emissions around 880 and 975 nm originated from the 4F3/2(Nd3+) and 2F5/2(Yb3+) levels when the glass structure changes to a glass ceramic structure due to the irradiation of the laser beam. The emission spectra before and after the irradiation with 2900 mW reveals that the desvitrification process made by the laser power beam has been successfully achieved. The intensities and lifetime changes of these levels inside and outside the hole made by the laser damage have been analyzed. These results confirm that nanocrystals of betaPbF2 have been created by the laser action confirming that the transition from glass to glass ceramic has been completed. These results are in agreement with the bulk spectroscopic measurements.