Theoretical and experimental study of ultraviolet broadband laser amplification using Ce:LiCAF crystal

Abstract

Trivalent cerium ion-doped lithium calcium aluminum fluoride (Ce:LiCAF) crystals have been demonstrated as efficient amplification gain media in the ultraviolet (UV) wavelength region. However, spectral characteristics in the multipass amplification process have not yet been studied theoretically and experimentally. This work investigates the spectral effects, including gain narrowing and spectral shifting using the chromatic Frantz–Nodvik model to simulate the amplification of broadband nanosecond UV pulses from a Ce:LiCAF crystal. From the simulation results, 5.5 mJ amplified pulses can be obtained using a 4-pass amplifier with seed pulses having 0.7 mJ pulse energy, 3 ns pulse duration and 288.5 nm peak wavelength. These values are in good agreement with experimental results. Seed pulses with peak wavelength of 290.0 nm and linewidth of 2.0 nm could be shifted to 289.8 nm peak wavelength and narrowed to 1.9 nm linewidth after 4-pass amplification. Accounting for the spectral effects will enable a more accurate prediction of the amplified pulses’ characteristics, thereby aiding the applications of high-power UV lasers.