Single Wavelength Operation of a Pulsed Water-Vapor Laser

Single wavelength operation on twenty-five emission lines in the range 23 to 57 μ was obtained by using three diffraction gratings to make the laser resonator frequency selective. This technique leads to new emission lines, enhanced output on weak lines, and identical pulse-to-pulse emission intensities. These results show that there are strong interactions among the transitions responsible for laser action. They are quantitatively consistent with the assumption that laser action is due to vibration-rotation transitions of the H2O molecule.