[en] We review the progress made on power scaling and compact and portable THz sources. By reversely stacking GaP plates, we improved photon conversion efficiency from 25% to 40%, which is the maximum value. As the number of the plates was increased from 4 to 5, the output power was decreased due to back conversion. We also investigated THz generation by mixing two frequencies generated by a single Nd:YLF solid-state laser. The average output power reached 1 μW. By introducing two Nd:YLF crystals, we significantly improved the output power to 4.5 μW. Such a configuration allowed us to generate different output frequencies. We have also reviewed our effort of making the THz source further compact by exploiting passively Q-switched laser pulses.