Crystals Shape Terahertz Pulses
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.
- pulse shaping
- The use of variations in the power supplied to a laser to change the shape of the output pulse. The technique is used in laser welding, for example, to condition a surface by preheating it at a low power or to anneal a surface at low power after the high-power weld is completed.
- terahertz radiation
- Electromagnetic radiation with frequencies between 300 GHz and 10 THz, and existing between regions of the electromagnetic spectrum that are typically classified as the far-infrared and microwave regions. Because terahertz waves have the ability to penetrate some solid materials, they have the potential for applications in medicine and surveillance.
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