Tunable narrowband terahertz generation by optical rectification in single domain lithium niobate crystal

During the last decades, narrowband terahertz (THz) radiation has attracted great interests in both fundamental and applied sciences. For many applications, the tunability of both central frequency and bandwidth of the narrowband THz radiation are required. In this study, a simple approach to generate high energy, frequency- and bandwidth- tunable multicycle THz pulses by optical rectification of pre-shaped fs-laser pulses in the single domain lithium niobate crystal is proposed and demonstrated. A one dimensional binary mask is used as the laser beam shapers. It is shown that the mask application is equivalent to spatial modulation of the crystal’s nonlinear coefficients, which allows using the technique of quasi-phase-matching and similar to the case that in periodically poled lithium niobate.