Second-harmonic generation by resonance absorption on nanoplasmas in the bulk of dielectrics

Second-harmonic (SH) radiation spectrum is an important diagnostic in nonlinear laser-plasma interactions. SH emission pattern provides useful information about the absorption mechanisms in the plasma. To date, experimental and theoretical works related to SH emission in plasmas are limited to plasmas at the surface of solids. Here, for the first time to our knowledge, we have experimentally characterized SH for plasmas inside the bulk of dielectrics with inversion symmetry. This is performed using single-shot femtosecond Bessel pulses in fused silica, glass and sapphire. This configuration creates dense nano-plasmas (diam. ≈ 200 to 500 nm) which relaxation in the material is capable of creating Warm Dense Matter [1] and lately opening voids [2] .