We demonstrate that the two basic physical mechanisms of terahertz (THz) generation in a femtosecond filament, namely, the free electron photocurrent and the nonlinear polarization of neutrals, can be identified through the spectral analysis of THz radiation. The contribution from the photocurrent peaks at the units of THz, while the neutrals yield the peak at the tens of THz. We suggest the practical implementation of such spectral analysis by varying the initial transform-limited laser pulse duration.
|Original language||English (US)|
|Number of pages||3|
|State||Published - Jun 1 2013|
Bibliographical noteFunding Information:
We wish to thank S. Efrima and B. Vlcková for numerous discussions and B. Vlcková for allowing us to visit her laboratory. This research has been supported by the Natural Sciences and Engineering Research Council of Canada.