Phase conjugation process at intracavity degenerate
four wave mixing of a long pulse CO2 laser radiation
in its active medium has been studied experimentally. Dependencies
of energetic and temporal characteristics of the phase
conjugation signal upon specific energy stored into electric
discharge, Q-factor of laser resonator, laser mixture composition
and pressure, interaction angle, optical delay between
probe and co-propagating waves, intensity ratio for these
waves J3/J1,
a degree of linear polarization, and laser spectrum are
analyzed. Reflectivity of the phase conjugation signal
is shown to increase with specific input energy rise and
a decrease of the ratio J3/J1,
being up to 7.5%. An increase of nitrogen content and a
decrease of helium content in the laser mixture results
in reflectivity rise and peculiar laser pulse profile with
two maximums being due to amplitude and phase nonlinearities
of the active medium. Specific input energy rise and an
increase of Q-factor leads to a decrease of response time
for the phase conjugation signal. Nonlinear properties
of degenerate four wave mixing on amplitude gain and phase
thermal diffraction gratings in the active medium of a
long pulse CO2 laser are analyzed theoretically.
An interconnection of nonlinear parameters of the amplifying
media with the temporal behavior of phase conjugation reflectivity
is determined. A comparison of the theoretical calculations
and the experimental data has been done.
The Use of Brillouin Enhanced Four Wave Mixing for Phase Conjugation of Laser Radiation.