High-energy multicolor femtosecond pulses in the deep-ultraviolet generated through four-wave mixing induced by three-color pulses

Multicolor deep-ultraviolet femtosecond pulses are generated in a spectral range of 220–300 nm with pulse energies exceeding 1 μJ. Pulses with shorter wavelengths are also generated with the shortest wavelength of 185 nm. These pulses are generated through cascaded four-wave mixing induced in hydrogen gas by use of three-color femtosecond pump pulses at 1200, 800, and 267 nm. The third pulse dramatically enhances the intensities of the multicolor deep-ultraviolet pulses. The cross-phase modulation induced by the two intense near-infrared pulses broadens the spectral width of each multicolor emission, resulting in a spectral width supporting a transform-limited duration shorter than 10 fs.