A review of laser-pumped infrared lasers

The lasing mechanisms are reviewed of molecules that have demonstrated laser action in the laboratories with laser emissions in the spectral range from 3 to 35 microns. A list of lasants and laser mechanisms are defined. The pumping sources for these lasers are mainly infrared lasers; however, the case in which excitation of bromine atoms at 2.71 microns by a flashlamp as energy input is also included in the review. A conceptual drawing of lasing mechanisms is shown. Three pumping mechanisms are shown, the first being the direct-pumped system in which the lasant molecule absorbs the infrared radiation from pump laser directly, and it is excited into the upper laser level from the ground state. The second system is the indirect-pumped system where the infrared-pump laser first excites an absorbing molecule which stores its vibrational energy. Through collision this energy is transferred to the lasant molecule, populating the upper laser level. In the third system, i.e., in a Br2-CO2 mixture, a flashlamp replaces the infrared laser as the pump source for the absorbing molecule.