Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We report the development at the VULCAN Nd:glass laser at the Rutherford Appleton Laboratory of chirped pulse amplification (CPA) operation at 620 fs to give 35 TW in a single large aperture beam, with focused intensities on target in excess of 1019 Wcm-2. We present a technique to optimise the parallelism of the compression gratings, whereby two CW alignment beams at wavelengths of 1053 nm and 1064 nm were injected into the compressor.

Abstract:

We have developed a model for the net induced gain as a function of pump fluence, based on a rate equation analysis of the populations of the 4f(n-1) 5d → 4f(n) level of the activator ions and of absorptive color centers. As an example, this has been applied to LiLuF4:Ce3+, in which we have also observed laser oscillation at 326.9 nm. The net gain is seen to rise rapidly with pump fluence before showing saturation and roll-off. This behavior can be explained by the creation of color centers that absorb strongly in the UV. We will present the results of similar measurements in the VUV on samples of LiYF4:Nd3+ and LaF3:Nd3+.