Detection of explosives (eg. in the field, baggage, or transit systems) has become an intense field of research over the last 15 years. Several physical (such as ion mobility spectrometry, mass spectrometry, and active neutron interrogation) and chemical (including calorimetry, fluorescence quenching, and electro-chemistry) techniques have been investigated as suitable detection mechanisms, and wide-ranging efforts have been made to improve the efficacy of these techniques. Each of these detection techniques can also be classified broadly as either a laser-based (i.e., terahertz, photoacoustic, Raman or laser-induced breakdown spectroscopy, or laser-induced fluorescence) or a non-laser-based method, each having their own merits and problems.