Tightly-focused laser beams can generate electromagnetic fields strong enough to cause ionization as in this example where a KrF excimer laser beam incident from the right has been focused to a spot size of 200 micro meter and a power density of 5 x 10^9 watts/cm^2 at a carbon surface. Much higher power laser systems are being studied for power generation via inertial confinement fusion in which case the focused laser beam(s) are incident symmetrically with enough intensity on a pellet target to initiate a controlled nuclear reaction.