Design of high-energy THz sources based on optical rectification

Tilting the pump pulse front has been proposed for efficient phase-matched THz generation by optical rectification (OR) of femtosecond laser pulses in LiNbO₃ (LN). This technique has recently resulted in generation of near-single-cycle THz pulses with energies on the 10-muJ scale. Such high-energy THz pulses have opened up the field of sub-picosecond THz nonlinear optics and spectroscopy. This paper reports on a guideline in designing high-energy ultrafast THz sources based on OR of femtosecond pulses and to assess the possibilities of further upscaling the THz energy. The key design issues are selection of the nonlinear material, phase matching, and optimal pumping conditions (wavelength, pulse duration, intensity). In order to compare the performance of different nonlinear materials at various pump wavelengths model calculations are used.