Photon beam that possesses an orbital angular momentum (OAM) exhibits an helical phase front and a donut shaped intensity profile. These peculiar properties have already enabled strong progress in several fields such as light manipulation or high density coding of information. Recently, the use of such OAM laser beam has been considered for laserplasma interaction and promising results have emerged from both theory and simulation. Thus, there is a growing need for experimental confirmation and observation of the propagation of an OAM laser within a plasma.
This experiment proposes to fill this gap by characterising the coupling between an OAM beam and a plasma and more specifically by evidencing that the OAM can be transferred from the laser beam to a plasma wave. This transfer will be driven by stimulated Raman scattering (SRS) that couples an OAM laser beam to an electron plasma wave (EPW) through the generation of a scattered electromagnetic wave. Measurement of this backscattered wave’s OAM state will enable to confirm that the EPW actually carry an OAM. Furthermore, the experiment will also focus on the characterisation the SRS in these conditions in order to possibly observe a new knob to harness this instability.
A secondary objective we intend to fulfill is to probe this OAM information directly into the plasma through Thomson scattering. Indeed, demonstrating that plasma could store OAM information could open the way to new laser-plasma applications.
ELFIE - S3-5/2019