Method and apparatus for hybrid photoacoustic compression machining in transparent materials using filamentation by burst ultrafast laser pulses

A method of laser processing a target, comprising the steps of:

• providing a beam having bursts of laser pulses, the target being made of a material that is transparent to the laser beam, each burst having between 2 and 50 laser pulses, each laser pulse having a pulse width of less than 10 nanoseconds;
• passing the laser beam through an aberrated focusing lens;
• focusing the laser beam using the aberrated focusing lens, the laser beam focused in a distributed manner along a longitudinal beam axis, the aberrations in the aberrated focusing lens developing the distributed focus;
• positioning the distributed focus with respect to the target;
• delivering the focused laser beam to the target, the focused laser beam having sufficient fluence to initiate Kerr effect self-focusing of the laser beam, thereby generating a laser filament that propagates along the longitudinal beam axis;
• and
• adjusting the pulse energy and distributed focusing to guide and maintain the laser filament between a desired point of initiation and a desired point of termination in the target, the laser filament creating a void coincident with the laser filament by annularly compressing the transparent material about the longitudinal beam axis.