<title>High-frequency temporal structure of laser and phase-conjugated signals at intracavity degenerate four-wave mixing of CO<formula><inf><roman>2</roman></inf></formula> and CO laser radiation in their inverted medium</title>

Abstract

The high frequency temporal structure of probe and phase conjugation (PC) signals under degenerate four-wave mixing (DFWM) of long pulse CO2 and CO laser radiation in their inverted media has been studied experimentally with nanosecond resolution over the full pulse length. The multiline and single spectral line pulses of electron-beam controlled discharge (EBCD) CO2 and CO lasers with pulse length of 10-20 ts and 200-300 s, accordingly, are characterized by complicated temporal behaviour with a periodic structure ( 100 ns) on account of mode beating with a depth of modulation up to 100%. On the round-trip period CO2 and CO laser pulse consists of several spikes (for free-running mode) or a single spike in case of mode locking with pulse length of ' 10 ns. A plasma mirror is used for CO2 laser to operate in the latter mode of operation. The time history of PC signal has a complicated behaviour and structure differed from that ofprobe laser signal on large ( 100 ns) and small (-10-100 ns) temporal scale. A relative influence of amplitude and phase mechanisms of creating diffraction gratings inside active medium, and also the influence of small scale and large scale gratings and spike synchronism conditions on the PC signal is discussed.