We propose to generate of ultrashort laser pulse harmonic radiation in a plasma optical waveguide generated by a preceeding laser pulse. The key idea is to increase the interaction length. We expect a good conversion efficiency since phase matching can be achieved in the plasma waveguide even in the presence of free electrons.
We plan to create optical channels by sending a first laser pulse on lithium atoms, singly ionizing them. A second pulse is injected in the formed channel in order to produce high order harmonics. We hope to extend the harmonic spectrum to unprecedently short wavelengths of coherent radiation than al- ready observed, due to the high intensity that can be tolerated by Li+.