"Complete" Spatio-Temporal Evolution of Ultrafast Dynamics of Extreme States of Matter in Intense Laser-Solid Interaction*

Intense femtosecond lasers interacting with solid targets create inhomogeneous, turbulent, and chaotic plasma flows. However, they can also produce various coherent excitations, including electron plasma waves (EPW) [1], coherent wave excitation (CWE) [2], and terahertz acoustics [3]. These have been observed in expanding plasma [3,4], but in the solid target’s interior, the matter is isochorically heated by energetic electrons, mimicking astrophysical scenarios. In these states, matter can host strong excitations, such as collisionless electrostatic shock waves (ESW), Filamentation, and Weibel instabilities, which can create very complex dynamics. Directly measuring their spatiotemporal evolution is extremely hard and remains almost unknown.

In this study, we present the first complete spatiotemporal evolution of the complex dynamics deep inside a solid, with sub-picosecond time resolution and micron spatial resolution. We employ pump-probe reflectometry, Doppler spectrometry, and Spectral Interferometry techniques to measure the periodic modulations in the amplitude, instantaneous frequency, and phase of the probe light induced by these excitations, enabling a direct and complete view of their evolution and decay.

Our measurements are essential in advancing the fundamental understanding of the dynamics of matter at extreme states, which is relevant to astrophysical scenarios.

References

[1]  A. Sandhu et. al., Phys. Rev. Lett. 95, 025005 (2005)

[2] F. Quéré et. al., Phys. Rev. Lett. 96, 125004 (2006)

[3] A. Adak et. al., Phys. Rev. Lett. 114, 115001 (2015)

[4] Kamlesh Jana et. al. Phys. Rev. Research 3, 033034 (2021)

[5] Kamlesh Jana et. al. AIP Advances 12, 095112 (2022)