Amplification of HOH carrying orbital angular momentum in plasma-based amplifiers

After 30 years since the discovery of the intrinsic orbital angular momentum (OAM) possessed by certain beams, a plethora of applications have been developed in diverse fields such as communications, astrophysics, and biochemistry. Meanwhile, injecting high-order harmonics (HOH) into krypton amplifier plasmas has emerged as a promising alternative to Free Electron Lasers (FEL) for generating table-top, XUV coherent radiation sources. This work brings together these two concepts and asks the following question: what happens when an HOH with OAM is injected into a plasma? Does the amplified beam retain the same OAM, or is this property affected? Understanding the OAM response to this process lays the foundation for new applications. Simulations using the 3D, time-dependent, Maxwell-Bloch code Dagon show that OAM is conserved in low-density plasmas. However, at higher densities, although the OAM is still preserved, the density profiles leave increasing footprints in phase patterns in the form of phase jumps curvature. Finally, a study has been conducted for a plasma with a waveguide, further supporting the potential of OAM for plasma diagnosis.