Terahertz radiation generation in waveguide partially filled with nonlinear crystal

We report on the effective generation pulse of THz radiation via optical rectification of femtosecond laser pulses in a nonlinear crystal. By placing the same nonlinear crystal in the free space and then inside the waveguide the phase-matching and consequently time and spectral features of the emitted THz field are changed. The rise of conversion efficiency in the order of magnitude has been obtained in waveguide structures partially filled with LiNbO
₃
crystal.