Spectral broadening of DUV pulses

Our strategy is to adopt spectral broadening methods to the UV, which are working well in the visible and near-IR spectral range.
For this aim let us compare the relevant aspects of laser-matter interaction for infrared and UV light:

Due to the much higher photon energy of UV radiation,

• the photoionization is much higher, and
• the nonlinear absorption of optical materials is much more severe in the UV than in he IR.

Due to the wavelength scaling,

• the critical power of self focusing ( ) is much lower,
• and upon focusing, the focal spot size ( ) and the focal depth (Rayleigh length, ) are smaller in the UV than in the IR.
  (Here f ^# denotes the f-number of the focusing geometry.)


• the material dispersion, and therefore the pulse distortion during propagation, is much higher in the UV.

The most successful method for spectral broadening of high-energy ultrashort pulses uses self-phase modulation in noble-gas-filled hollow fibers .