Remote terahertz wave sensing using laser-induced fluorescence

Remote terahertz (THz) wave spectroscopy holds great potential in the applications in homeland security and environmental monitor. However, broadband THz wave sensing at standoff distance has remained long-existing challenge due to the strong ambient water vapor absorption in THz frequency region. Here we present an “all-optical” technique of broadband terahertz wave remote sensing through coherent manipulation of the fluorescence emission from asymmetrically ionized gases. Owing to the high atmospheric transparency and omni-directional emission pattern of fluorescence, this technique can be used for remote sensing with advantages of minimal water vapor attenuation and unlimited directionality for optical signal collection. Coherent THz wave detection at a distance of 10 meters has been successfully demonstrated.