High-frequency temporal structure of laser and phase-conjugated signals in intracavity degenerate four-wave mixing of radiation from electron-beam-controlled discharge CO2 and CO lasers in their active media

The high-frequency temporal structure of probe-laser and phase-conjugated signals, generated in the course of degenerate four-wave mixing of long pulses from CO₂ and CO lasers in their own inverted media, was investigated experimentally with nanosecond resolution throughout the whole pulse. Single-frequency (corresponding to one vibrational — rotational transition) and multifrequency pulses of ~10 – 20 μs and ~200 – 300 μs durations, generated respectively by electron-beam-controlled discharge CO₂ and CO lasers, had a complex temporal dynamics with a depth of modulation up to 100%. In one round-trip period (~100 ns) the pulses from these CO₂ and CO lasers consisted of several spikes (free-running mode) or of one spike (self-mode-locking with the aid of a plasma mirror) of τ_0.1 ~10 ns duration. The temporal dynamics of the phase-conjugated signal also had a complex structure, differing from the probe signal structure over longer (in excess of 100 ns) and shorter time intervals. The relative influence of the amplitude and phase mechanisms of the formation of transient diffraction gratings in the active medium, and also the influence of large- and small-scale diffraction gratings, and of the temporal synchronism on the dynamics of the phase-conjugated signal were considered.