Two sapphire substrates are tightly bonded through a BaTiAl6O12-glass thin film, by irradiation with a
nanosecond laser. After the laser process, the composition of the glass sealant changes, due to in-
corporation of Al2O3 from the upper substrate. After annealing of the bonded samples (950 °C for
30 minutes) crystalline structures are observed by TEM which are attributed to crystalline BaTiAl6O12.
These crystals together with Al2O3:Ti centers are the responsible of the observed strong blue lumines-
cence of the laser irradiated region upon UV excitation. The structural and optical characterizations of the
bonded samples clarify the laser soldering procedure as well as the origin of the luminescence. Bond
quality and bond strength were evaluated by scanning acoustic microscopy (SAM) and tensile stress of nearly 13 MPa, which is an acceptable value for glass sealants.