Abstract: It is proposed to replace the traditional
counter-propagating laser seed in backward Raman amplifiers with a
plasma wave seed. In the linear regime, namely for constant pump
amplitude, a plasma wave seed may be found by construction that
strictly produces the same output pulse as does a
counter-propagating laser seed. In the nonlinear regime, or
pump-depletion regime, the plasma-wave initiated output pulse can be
shown numerically to approach the same self-similar attractor
solution for the corresponding laser seed. In addition, chirping the
plasma wave wavelength can produce the same benefi cial e ects as
chirping the seed wave frequency. This methodology is attractive
because it avoids issues in preparing and synchronizing a
frequency-shifted laser seed.