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Recent progress on efficient generation of monochromatic THz pulses based on difference-frequency generation

We review our recent efforts on power scaling of THz pulses generated by several nonlinear crystals. By using a single GaP crystal and stacking three GaP plates, we have significantly increased the output peak power to as high as 722 W and 2.36 kW, respectively. On the other hand, by using CO2 laser pulses, we have obtained the average output power of 260 μW. We have also used these laser pulses to scale up the output power for the THz pulses to 29.8 μW by stacking GaAs wafers. Indeed, by stacking up to ten wafers, we have increased the output power by a factor of 160. Finally, by using ultrafast laser pulses, we have achieved record-high output powers for the THz pulses generated from multi-period periodically-poled LiNbO3 crystals based on a backward configuration. The highest output power obtained by us so far is 10.7 μW.