Multipass CO2 amplifier with four-wave phase-conjugating mirrors

A narrow-band adaptive multipass amplifier with four-wave phase-conjugating mirrors was developed. Pumping of these mirrors with radiations from two independent master oscillators was used in a three-pass CO₂ amplifier with two four-wave mirrors operating on the basis of a thermal nonlinearity of a liquid (CCl₄). The total gain achieved in this way was 2×10¹¹. Two-pass and four-pass operation was also achieved and the corresponding gains were 1.5×10⁷ and 5×10⁹, respectively.