Remotely pumped stimulated emission at 337 nm in atmospheric nitrogen

We report the observation of forward-propagating UV stimulated emission in atmospheric nitrogen pumped, at a standoff distance of 2.6 m, by an energetic laser pulse at a wavelength of 1053 nm and with the duration in the picosecond range. The generated optical gain at 337 nm is seeded by third harmonic of the pump beam. This demonstration is an important step towards the development of techniques for standoff optical sensing in the atmosphere.