Small bubbles can be observed in both sapphire and Ti-sapphire bulk crystals grown by Czochralski technique
(Cz). Various thickness of wafers cut from the grown ingots were studied by optical microscopy.
Bubbles distribution has different regulation in sapphire and Ti-sapphire crystals. All bubbles are spherical
and have a diameter range from 2 lm to 5 lm in sapphire crystals while 10–45 lm in Ti-doped sapphire
crystals. Some adjacent bubbles congregated into defects present various sizes and shape. The
bubbles density increases as a function of pulling rate and rotation rate. The effect of bubbles on optical
characterizations of Ti-sapphire crystals has been studied.