Demonstration of a Gain-Saturated 8.8 nm Table-Top Soft X-Ray Laser at 1 Hz Repetition Rate

There is significant interest in extending compact plasma-based lasers to sub-10 nm wavelengths to be able to realize table-top experiments with high intensity laser pulses at these wavelengths. However, the steep wavelength scaling of the optical pump laser energy necessary imposes a challenge and has limited gain-saturated table-top lasers that can operated at high repetition rate to wavelength above 10.9 nm [1]. We report the demonstration of gain-saturated laser operation at $\lambda $= 8.85 nm in the 4d$^{1}$S$_{0}\to $4p$^{1}$P$_{1}$ line of nickel-like lanthanum ions in a plasma column created at 1 Hz repetition rate by focusing pulses from a Ti:Sapphire laser with a total of 7.5 J energy onto a lanthanum slab. We have observed strong lasing at 8.5 nm in nickel-like cerium. \\[4pt] [1] D. Alessi, D. H. Martz, Y. Wang, M. Berrill, B. M. Luther, and J. J. Rocca. Optics. Lett. Vol. 35, 414 (2010).