Method of material processing by laser filamentation

A method of preparing a substrate for cleavage, the method comprising the steps of:

• irradiating the substrate with a burst of pulses of a focused laser beam, wherein the substrate is transparent to the focused laser beam, wherein a time delay between successive pulses in the burst of pulses is less than a time duration over which relaxation of one or more material modification dynamics occurs, and wherein the burst of pulses have an energy and pulse duration selected to produce a filament within the substrate;
• translating the substrate relative to the focused laser beam to irradiate the substrate and produce an additional filament at one or more additional locations;
• wherein the filaments form an array defining an internally scribed path for cleaving the substrate;
• wherein each burst of pulses is focused to provide a sufficient beam intensity within the substrate to cause self-focusing of the focused laser beam over an extended laser interaction focal volume, thereby producing a plasma channel while avoiding optical breakdown, such that substantially uniform modification of the material occurs along the beam path, thereby forming a single continuous filament within the substrate;
• and
• wherein each single continuous filament is formed with a sufficient length to facilitate cleavage of the substrate without requiring repeat passes of the laser over the same region.