Observation of extremely large nonlinear refractive index in water vapor in THz regime (Conference Presentation)

Terahertz (THz) nonlinear optics is an emerging field thanks to recent developments in the generation of intense THz pulses. THz radiation interacts with the vibrational/rotational resonances of molecules. For example, water molecules in the atmosphere show a very rich absorption spectrum with hundreds of sharp resonances below 3 THz. We report on the first experimental demonstration of the nonlinear interaction of THz pulses with water vapor. We observed a strong nonlinear response of the vibration/rotation resonances to the THz pulses. The frequency response of the nonlinear Kerr coefficient is extracted from the experimental results.