Abstract

To control the carrier envelope phase (CEP) is very important when we employ a few cycle electro-magnetic pulses for nonlinear phenomena such as higher-order harmonic generation [1], strong-field ionization and dissociation[2], and population transfer between two bound states [3]. Hence it should also be essential for nonlinear spectroscopy in the terahertz (THz) frequency region. Recently, the generation of extremely intense monocycle THz pulses has been established with the nonresonant optical rectification process and various THz nonlinear spectroscopies have been demonstrated [4]. The CEP of such THz pulses is originally locked in principle. However, to change the CEP arbitrarily has been impossible so far. To overcome the task, we focused our attention on the novel property of a series of parallel plate waveguides. For the TE mode in the waveguide [5], the phase velocity v_p is larger than the light velocity c in the vacuum while the group velocity v_g is smaller. If the chirp caused by the group velocity dispersion is negligible, the CEP of the THz pulse is changed during its propagation in the dispersive medium.

© 2013 IEEE