On the night of July 20, 2012, the laser system of the Berkeley Lab Laser Accelerator (BELLA), which is nearing completion at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), delivered a petawatt of power in a pulse just 40 femtoseconds long at a pulse rate of one hertz – one pulse every second. A petawatt is 10^15 watts, a quadrillion watts, and a femtosecond is 10^-15 second, a quadrillionth of a second. No other laser system has achieved this peak power at this rapid pulse rate.
Impressive. Multiplying the two, we see that this is ~40 Joules of energy per pulse, which isn’t a lot of energy, but getting the pulses short and repeating them is the hard part. Lots of interesting things happen when you get a large energy density — there are nonlinear processes that depend on some exponent of field strength.