We demonstrate intense pulse guiding in efficient femtosecond end-pumped waveguides generated in clustered gases. This novel scheme provides a route to significantly lower on-axis plasma density ($<{10}^{18}{\mathrm{cm}}^{-3}$) more than is feasible in conventional hydrodynamic plasma waveguides. Self-focused propagation and strong absorption of intense femtosecond laser pulses are used to produce long centimeter scale channels in an argon cluster jet, and a subsequent pulse is guided with $3\times {10}^{17}\mathrm{W}{\mathrm{cm}}^{-2}$ intensity and $\sim 50\%$ coupling efficiency. Preliminary results with hydrogen clusters also show guiding.

• Received 12 October 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.205004