Chirped-pulse amplification in a CO2 laser

Chirped-pulse amplification (CPA) is an integral part of present-day ultra-intense laser systems that normally employ near-infrared (similar to 1 mu m) solid-state lasers. The recently revived interest in expanding the reach of strong-field laser physics into the mid-infrared (mid-IR) spectral domain directs our attention to 9-11 mu m carbon-dioxide (CO2) lasers for which progress to reaching high peak intensities has been limited so far. We propose that employing the CPA technique will allow us to realize a new breakthrough toward multiterawatt, ultrafast mid-IR lasers; here we report, to our knowledge, the first implementation of this method for a CO2 laser. Our stretching of a 1 ps, 9 mu m pulse to 80 ps improved energy extraction from a regenerative CO2 laser amplifier by 1 order of magnitude. We explain this accomplishment by the reduction in nonlinear absorption and refraction on the amplifier's optical elements. We consider these findings as being a pivotal step toward establishing next-generation ultra-intense CO2 CPA laser systems for strong-field mid-IR research and its applications. (C) 2015 Optical Society of America