Ultrafast Physics of Bessel Beam Interaction with Solid Dielectrics: Dense Plasma Formation, Second Harmonic and THz Radiation

The creation of dense plasmas inside solids by ultrafast lasers is crucial for applications such as EUV radiation, warm dense matter study or laser materials processing. It is conventionally difficult to create large volumes of dense plasmas inside the bulk of dielectrics to benefit from pressure confinement. Here, we demonstrate that femtosecond Bessel beams generate overdense plasmas in single pulse over a very long, sub-wavelength rod. We report here on experimental and numerical investigations on the rich physics at play, that leads to extreme energy density deposition inside the solid, formation of plasma double layer, second harmonic and terahertz generation.