Reflection and backscattering of IR light from free space laser plasmas in air

The detection of remotely generated, isotropically emitting signals is limited by the inverse square law relation of optical power and distance. In this work we investigate the use of free space laser plasmas, capable of partial reflection and scattering of incident light, to enhance detection of weak spectroscopic signals. Here, we study the properties of a probe signal reflected from a single laser generated plasmas in air utilizing a pump-probe scheme. Nanosecond and femtosecond laser generated plasmas are probed by a low energy nanosecond Optical Parametric Oscillator (OPO) laser capable of continuously variable emission in the 1.1-4.4 μm band. The transmissivity and reflectivity are measured and reported as functions of incident wavelength, pump-probe delay, and probe position along the pump beam’s optic axis. Implications to optical sensing technologies are discussed.