Generating optical supercontinuum and frequency comb in tenuous plasmas

Wideband laser spectra with high intensities are capable of overcoming plasma instabilities and enable efficient laser power delivery. Focusing on one-dimensional effects, we identify two strong optical nonlinearities, namely, four-wave mixing (including self-phase modulation) and forward Raman scattering, for creating octave-wide spectra. PIC simulations demonstrate that the spectrum of a bicolor laser at 10¹⁶-10¹⁷ W/cm² can be broadened by nearly two orders of magnitude after propagating through a few-centimeter-long plasma of density 10¹⁷-10¹⁸ cm^-3. This talk will discuss the two operation regimes of laser spectra broadening and key properties of each regime.