In our recent work, we have generated the shortest wavelengths from periodically-poled lithium niobate (PPLN) in the vicinity of 62.5 microns at the poling period of 7.1 microns. We have demonstrated large enhancements in the output powers from three gratings. For the long-poling periods, we have generated THz radiation with output wavelengths in the range of 126-1382 μm and output powers as high as 432 μW, corresponding to the photon conversion efficiency of 29%. We have also efficiently generated far-infrared radiation at the wavelengths centered at 20.8 microns in the vicinity of one of the polariton resonances of lithium niobate. Such an efficient nonlinear conversion is made possible by exploiting phase-matching for difference-frequency generation in lithium niobate. The highest peak power reached 233 W. These wavelengths correspond to the shortest wavelength in the terahertz region and longest wavelength in the mid-infrared/far-infrared regions from lithium niobate, respectively.