Four-wave frequency mixing in gas-filled waveguides

A study is made of the characteristics of nonlinear frequency mixing in gas-filled waveguides. It is shown that when the wave matching conditions are satisfied, the conversion efficiency can increase significantly (by a factor up to 10²–10⁴) compared with the conversion under hard focusing conditions. An analysis is made of the advantages of waveguides in the generation of short-wavelength radiation in the vacuum range. The feasibility of experimental implementation of pulsed and cw operation is considered.