Forward Raman plasma holography for waveform encoding and density-uniformity diagnostics

Holographic recording and retrieval based on Raman scattering provide a flexible route for optical information processing in plasmas. In this work, we investigate plasma holography based on forward Raman scattering and systematically examine the effects of plasma density inhomogeneity. In uniform plasmas, optical information carried by an information wave can be recorded in an electron plasma wave (EPW) and subsequently retrieved by a reference pulse. When plasma density inhomogeneity is introduced, the holographic process exhibits a pronounced asymmetry between the recording and retrieval stages. While EPW excitation during recording remains robust against moderate density gradients, the retrieval process is strongly limited by phase mismatch induced by spatial inhomogeneity. This intrinsic asymmetry enables spatially selective removal of the reconstructed optical signal through tailored plasma density profiles. As a result, forward-Raman-based plasma holography supports a range of applications in inhomogeneous plasmas, including waveform encoding through the selective removal and insertion of pulse segments, as well as density-uniformity diagnostics in large-scale plasmas. These results highlight the potential of forward Raman scattering as a versatile platform for holographic control and diagnostics in complex plasma environments.