Efficient generation of high-power single-cycle THz pulses from single optical beam in second-order nonlinear medium

Summary form only given. During this presentation, we show that the coherence lengths for the THz generation based on difference-frequency generation within each ultrafast optical pulse can be sufficiently long for a wide bandwidth around each phase-matching wavelength due to a slight dispersion in the THz region (i.e. what-we-define "quasi-phase-matching"). As a result, quasi-single-cycle THz pulses can be efficiently generated. An efficient conversion for the parametric process is made possible not only by utilizing the quasi-phase-matching but also by optimizing the pulse width for each peak THz frequency. We have investigated the strong pump region and found the limits to the conversion efficiencies in order to efficiently generate very high peak intensities for the THz waves to explore a nonlinear regime of the THz interactions. Moreover, we have introduced effective third-order nonlinearities by cascading two second-order THz parametric processes and estimated their values.