Laser sources for efficient two-step positronium excitation to Rydberg states

Antihydrogen production by charge exchange reaction between Positronium atoms and antiprotons benefits from an efficient excitation of Positronium atoms to high-n levels (Rydberg levels). A two-step optical excitation, the first from ground to n = 3 and the second from this level to a Rydberg level, is proposed and a proper laser system to be developed is discussed. The requirements on the energy and bandwidth of the excitation laser suggest the use of optical parametric generation technology for both wavelengths. The laser system is composed of two subsystems: one for the generation of 205 nm radiation and the other for the generation of 1670 nm radiation. We report on the progress towards the realization of the short wavelength source.