Building high energy and high repetition lasers using current state of the art technologies have limitations.  They would require large aperture gain medium and optics, which are challenging to manufacture and limit the type of gain medium.  With large components, there is limited transverse gain control and low efficiency.  Additionally, as with any laser, some of the pump energy is converted to waste heat rather than laser power. The residual heat in an Inertial Fusion Energy (IFE)-class or other high rep-rate/average power laser will significantly deteriorate performance by inducing thermal lensing and stress that eventually causes failure. 

There is a need for innovative approaches to overcome these disadvantages with particular focus on effective heat extraction from laser gain medium at high power operations (>kJ, up to and beyond 10 Hz rep rate) and controlling parasitic lasing - losses due to traverse amplified spontaneous emission (TASE) of the amplifier, which reduces stored energy after pumping.