Standoff Sensing for Low Volatility Chemicals Using Terahertz Radiation-Enhanced-Emission-of-Fluorescence

We propose a new active optical method to measure time-domain waveform of THz pulse in the vicinity of the target in an omni-directional manner. This method utilizes the THz radiation-enhanced-emission-of-fluorescence from laser-induced air plasma to detect the THz field, which enables the standoff sensing for low volatility chemicals using THz spectroscopy. We have demonstrated its capability of broadband high resolution spectroscopic recognition by detecting the explosive molecules and some other molecules. The handheld sensing device using this method is featured with several advantages such as: high safety, point detection capability, broadband sensing range, real-time monitoring, unlimited collection angel and remote sensing ability.