Design of a beam separator for high-order harmonics below 10 nm

Abstract

High-order harmonics are a relevant source of coherent extreme-ultraviolet and soft x-ray radiation of very short time duration, super spatial coherence and high peak brilliance. For their practical use however, the problem of the co-propagation of the high-energy pumping beam with the generated harmonics has to be solved. For this purpose a beam separator has to be used, with high damage threshold, high attenuation of the pump pulse, high throughput in the extreme-ultraviolet and tunability in a broad spectral region. In this work we present the design of a beam separator for ultrashort high-order harmonics with two diffraction gratings. The system can be designed for any wavelength in the 2-40 nm region, is efficient and robust with respect also to very powerful laser sources. Both temporal and spatial chirping effects are analyzed.