Colorful light channel for femtosecond laser filamentation in nanoparticle colloidal solutions

We investigate the femtosecond laser filamentation in nanoparticle colloidal solutions. Colloidal solutions of water doped with gold (Au), silver (Ag), copper (Cu), and calcium carbonate (CaCO3) nanospheres under different sizes and concentrations were experimentally studied. A cyan–red light path was visualized, and the generated supercontinuum spectra spanning from 400 nm to 950 nm were obtained. It was found that the energy losses and frequency-dependent scattering are necessary prerequisites for generating a colorful light path.