Coherent detection of ultrabroadband coherent infrared pulses up to 150 THz using air

We coherently detected the ultrabroadband infrared pulse generated from air plasma in the spectral range of 1-150 THz through field-induced second harmonic generation in air. Pump and probe pulses with duration of 10 fs were produced with hollow fiber compression. This result proves the advantage of using air for coherent detection over conventional electro-optic sampling in terms of wide spectral range as well as high sensitivity. We are integrating this system in a pump and probe measurement system, which will be a powerful tool for studying optical property of materials.