Systems and methods for laser drilling provide laser beam energy modification to reduce (e.g., eliminate or minimize) back-wall strikes during laser drilling. The systems and methods modify the process laser beam energy such that a beam energy at a central region of the process laser beam is less than a beam energy at an outer region of the process laser beam. In one example, the modified process beam has zero beam energy at the central region, thereby providing a "donut mode." The laser beam energy modification may be achieved by detuning a fiber coupler in the Z axis such that laser energy is coupled into a cladding layer of the process fiber coupled to the laser fiber via the fiber coupler.
