Narrow-Band Terahertz Pulse Generation in Lithium Niobate Crystal Using Phase Mask

Below, we theoretically study the generation of narrowband terahertz (THz) radiation by optical rectification in an artificial periodically poled lithium niobate (LN) crystal with a wide aperture. The latter is formed by placing a multi-slit phase mask in front of a conventional (single-domain) LN crystal. It is shown that the bandwidth of THz generation can be varied over a wide range by changing the linear size of the pump beam in the crystal. In addition, it is possible to tune up the generation frequency in the range of 0.4–0.8 THz by building a mask image in the crystal with different magnifications. According to estimates, the energy of narrowband THz pulses at a frequency of 0.5 THz in a stoichiometric LN crystal at a temperature of 100 K is about 265 μJ for a pump pulse energy of 220 mJ.