Prospects for the development of high-order parametric amplifiers as an alt
ernative to the existing inversion-based soft-x-ray lasers are analyzed. We
show how the problem of phase matching can be solved. The possibility of g
ain transfer from a low-order parametric process to the high-order process
is discussed. Initial encouraging experimental results toward the demonstra
tion of high-order parametric amplifiers are reported. (C) 1999 Optical Soc
iety of America [S0740-3224(99)02809-X].