Scaling of high-order harmonic efficiencies with visible wavelength drivers: A route to efficient extreme ultraviolet sources

Scaling of high-order harmonic generation (HHG) efficiency versus drive wavelength is experimentally studied using 800 and 400 nm pulses and theoretically modeled for visible drive wavelength. We demonstrate good agreement of experimental results with the calculations from a recently established semianalytic HHG model and discuss the feasibility of efficient-HHG-based extreme ultraviolet sources driven by visible ultrafast lasers. Our study shows that efficiencies of $>10−5$ can be achieved at $∼90eV$ by selecting appropriate drive wavelengths with He under good phase matching conditions.