Ultraviolet laser pulse amplification in Ce:LLF

Experimental and numerical modeling studies have been carried out in order to characterize the suitability of Ce:LLF as an amplifier medium for UV ultrashort pulses. The spontaneous lifetime, gain cross-section and absorption cross-section were measured for pumping at 248 nm. A sigma polarized transverse pump energy fluence of 1.3 J/cm² at 248 nm gave a single pass gain coefficient of 4.7 cm^-1 at 308 nm (pi polarization) in a 7.5 mm long crystal. In order to assess application to a high intensity ultrashort laser system, a three stage Ce:LLF chirped pulse amplification system was numerically modelled. The results indicated that a 60 fs 20 μJ seed pulse could be amplified to an output energy of 800 mJ (after pulse compression), resulting in a peak power of 13 TW using 5.1 J of KrF pump energy.