The scientists at Institute of Electronic Structure & Laser in Greece and Max-Planck-Institut für Quantenoptik in Germany reported their research results in recent issue of Nature Physics.
Continuing efforts in ultrashort pulse engineering have recently led to the breakthroughs of the generation of attosecond (10^-18 s) pulse trains and isolated pulses. Although trains of multiple pulses can be generated through the interaction of many-optical-cycle pulses with gases—a process that has led to intense extreme-ultraviolet emission—the generation of isolated high-intensity pulses, which requires few-cycle driving pulses, remains a challenge. Here, we report a vital step towards the generation of such pulses, the production of broad continuum extreme-ultraviolet emission using a high-intensity, many-cycle, infrared pulsed laser, through the interferometric modulation of the ellipticity of 50-fs-long driving pulses. The increasing availability of high-power many-cycle lasers and their potential use in the construction of intense attosecond radiation—with either gas or solid-surface targets—offer exciting opportunities for multiphoton extreme-ultraviolet-pump–extreme-ultraviolet-probe studies of laser–matter and laser–plasma interactions.
The Dual Michelson interferometer device is shown in the left picture, BS: beam splitters. M: flat mirrors. TS1,2,3: piezoelectric translation stages. A: intensity attenuator. First and second MI: first and second Michelson interferometers.