摘要
The temporal and spectral characteristics are compared for the THz wave radiation generated under optical rectification of the femtosecond laser pulses in samples of two different types of periodically poled lithium niobate (PPLN) crystals. Narrow-area post-growth PPLN samples were fabricated by applying the standard electrical poling technique. Large-area in-growth samples were cut from periodically poled Mg:Y:LiNbO 3 crystals obtained directly within the off-center Czochralski growth procedure. It is shown that the generation efficiencies of the post-growth samples and the most regular parts of the in-growth crystals are of the same order. The stochastic character of the in-growth samples does not affect appreciably the width of the generated spectrum, but decreases the peak power. The importance of the transverse size of the PPLN samples in both generation and detection tasks is analyzed. © 2013 Astro Ltd.