Methods for ultrashort pulse laser processing of optically transparent
materials. A method for scribing transparent materials uses ultrashort
laser pulses to create multiple scribe features with a single pass of the
laser beam across the material, with at least one of the scribe features
being formed below the surface of the material. This enables clean
breaking of transparent materials at a higher speed than conventional
techniques. Slightly modifying the ultrashort pulse laser processing
conditions produces sub-surface marks. When properly arranged, these
marks are clearly visible with side-illumination and not clearly visible
without side-illumination. In addition, a method for welding transparent
materials uses ultrashort laser pulses to create a bond through localized
heating. The ultrashort pulse duration causes nonlinear absorption of the
laser radiation, and the high repetition rate of the laser causes
pulse-to-pulse accumulation of heat within the materials. The laser is
focused near the interface of the materials, generating a high energy
fluence at the region to be welded. This minimizes damage to the rest of
the material and enables fine weld lines.