ИСТИНА

A theoretical model has been proposed for calculation of the frequency-angular distribution of THz radiation,taking into account the influence of nonlinear processes that occur with violation of the exact longitudinal phase matching condition. Examples of the angular distributions are numerically calculated and analyzed for the radiation power densities at 1 THz inside the crystal, inside and outside the Si couplers with different exit surfaces. Experimentally, the temporal dependences of THz electric field and the spectral power density distributions were measured for diff erent shapes of the Si couplers. Comparison of the theoretical and experimental results demonstrates advantages of the convex output surfaces of Si couplers and validity of thedeveloped theoretical approach for further modeling the improved Si elements.