Use of periodically poled nonlinear materials for the generation of ultrashort pulses of mid- and far-infrared radiation

We report on the generation of mid- and far-infrared radiation using periodically poled materials. In particular, cw mode-locked fs optical parametric oscillators based on (PPLN) periodically poled LiNbO/sub 3/:MgO with strongly reduced photorefractivity and optical rectification in PPLN for the generation of tunable narrowband THz radiation will be discussed.