Demonstration of an all-diode pumped soft x-ray laser and other advances in table-top soft x-ray lasers

We report the first demonstration of an all-diode-pumped soft x-ray laser system. Lasing was achieved in the λ = 18.9 nm line of Ni-like Mo ions pumping with a diode-pumped cryo-cooled Yb:YAG chirped-pulse-amplification laser system that generates 1 J pulses of 8.5 ps duration. Driver lasers pump by diodes opens the possibility to develop a new generation more compact soft x-ray lasers operating at significantly increased repetition rates for applications. In a separate development we have demonstrated a gain-saturated table-top λ=10.9 nm laser operating at 1 Hz repetition rate with an average power of 1 μW in the 4d¹S₀→4p¹P₁ transition of nickel-like Te and observed lasing at 8.8 nm in nickel-like La in plasmas exited by a Ti:sapphire laser. Utilizing the same pump laser we obtained laser pulse energies of up to 10 μJ and an average power of 20 μW in the 13.9 nm line of Ni-like Ag. In a third set of experiments we characterized the beam properties of an injection-seeded soft x-ray laser based on the amplification of high harmonic pulses in a solid-target plasma soft x-ray laser amplifier. Injection-seeding is shown to dramatically improve the far-field laser beam profile and reduce the beam divergence. Measurements and 2-dimensional simulations for a 13.9 nm nickel-like Ag amplifier show that the amplified beam divergence depends strongly on the seed divergence, and can therefore be tailored by selecting it.