Trace gas measurement for security applications with injection-seeded terahertz-wave parametric generation

We proposed trace gas measurement for security applications using an injection-seeded terahertz (THz)-wave parametric generation (is-TPG). To achieve high sensitivity and robustness, a monolithic cylinder as a multi-pass cell for THz waves was designed and the detectability of 0.5 ppm for methanol was achieved. The results indicate that is-Tpgsystem provides sensitive detections and identifications for molecules in atmosphere to make secure society.