A number of petawatt or sub-petawatt laser systems are notable for being capable of operating at high repetition rates (HRR). These laser systems are high average power (HAP) lasers, delivering high power when averaged over macroscopic time scale yet still maintaining terawatt or petawatt peak power within a single pulse. HAP petawatt lasers are crucial for any future applications of petawatt laser systems such as compact light sources, next-generation accelerators, or proton source for radiotherapy; in scientific research facilities, they also greatly improve experiment efficiency by enabling a much large set of experimental data to be collected within the same amount of beam time. On the other hand, designing and operating petawatt laser systems at high repetition rate presents an immense engineering challenge, as the laser system must handle large amounts of excessive heat when pumped at a much higher frequency as well as thermal effects that degrades beam quality. In recent years, advances in high-power laser technology, such as pumping schemes,
pump light sources, and cyrogenic cooling, led to the emergence of a new class of HAP laser systems. Addressing the important of high average power lasers as the future development of petawatt lasers, the following list contains a list of laser systems with peak power >=100 TW and average power >=100 W. Note that some lasers in the list are already petawatt-class lasers. == Gallery ==