Generation of high-energy ultrashort DUV pulses

The generation of ultrashort (sub-20 fs) DUV pulses is rather challenging because only a few exotic materials exist which can be used for light amplification in this wavelength range, but their bandwidth does not support pulses shorter than ~100 fs. Therefore the usual approach has been to extend the range of operation of standard near-IR Ti:sapphire laser systems to the UV-DUV spectral range by applying ultra-broadband frequency conversion techniques.

Common scheme for short pulse generation in the DUV
(The stages marked with dashed border are optional.)

The most critical part of this approach is the ultra-broadband frequency conversion which can be done e.g. by four wave mixing in noble-gas-filled hollow fibers or in filaments, by achromatic phase matching in nonlinear optical crystals, or by harmonic generation in gas cells or gas jets. This way sub-20 fs pulses could be generated in the DUV, however the pulse energy has been limited to a few microjoules.

Our novel approach is to apply a spectral broadening technique to moderately short but energetic DUV pulses. Theoretically much higher energies can be achieved in this way, because it is not the pulse generation but only the spectral broadening which is governed by a low-efficiency third order nonlinear process.

Our novel scheme for short pulse generation in the DUV
(The stage marked with dashed border is optional.)

In this approach the key step is the spectral broadening of the energetic DUV pulses.