Laser-Induced Periodical Structures Fabrication for Third Harmonic Generation

We propose a novel strategy for self-adjusted fabrication of large-scale array of resonant silicon nanoparticles (metasurface) on a thin silicon film. The self-adjusting mechanism is based on the effect of resonant nanogratings formation under intense multishot femtosecond irradiation of a thin silicon film. The resulting metasurfaces allow for generation of ultraviolet laser pulses at a wavelength of 270 nm with conversion efficiency up to 10^-6 and high peak (≈100 kW/sm²) and average power (≈1.5 μW). Such high peak power from ultrathin metasurface makes the generated UV pulses applicable in a wide range of applications: precise nanolithography, ultrafast photoexcitation etc.