Scientists at Oregon State University in Corvallis have experimentally and theoretically examined the pulse shaping of terahertz radiation by optical rectification in poled lithium niobate. They suggest that the technique, which they reported in the Jan. 13 issue of Applied Physics Letters, will find applications in terahertz spectroscopy.In the experiments, the researchers focused 100-fs pulses of 800-nm radiation from a Ti:sapphire oscillator into engineered stacks of poled LiNbO3 to produce terahertz waveforms that corresponded to the domain structures of the crystal. Although the results agreed qualitatively with their calculations, they discovered quantitative errors that they attributed to oversimplifications in the model.The scientists noted that successful pulse shaping will require a better understanding of the linear dispersion of the material in the terahertz region.