Excimer laser ablation of Nd: YAG and Nd: glass

The excimer laser ablation of neodymium (Nd) doped glass and Nd doped yttrium aluminium garnet (YAG) crystals has been performed using 193 and 248 nm radiation. Etch rate versus fluence (energy per unit area) plots show that the ablation thresholds are in the range 0.5–1.6 J/cm2. The effective absorption coefficients thus measured were found to be of the order of 104–105 cm−1, two or three orders of magnitude greater than the small signal absorption coefficient. The ablation of Nd: YAG and Nd: glass at 193 nm produced etch pits of superior quality to those pits produced using 248 nm laser exposure. Time integrated emission spectra of the ablated plumes in vacuum showed up to one hundred lines for Nd: YAG at both wavelengths while the Nd: glass spectra were simpler, considerably so for 248 nm irradiation.