Terahertz Measurements for Material Research

• A single terahertz measurement determines the complex refractive index of samples
• This provides structural information e.g. on polymers or composite materials
• Active fields of research include liquid crystals, semiconductors and metamaterials
• Recommended systems: TeraFlash pro, Imaging Extension, TeraFlash smart, TeraScan

Applications of terahertz spectroscopy

Various applications of terahertz spectroscopy exist, as not only gases, but also many organic solids show absorption signatures at terahertz frequencies. Complementing the information gained from amplitude data, refractive index measurements help unveil the properties of samples: For polymers, the variation of the refractive index with temperature uncovers minute structural changes. For fiber-reinforced plastics, the refractive index yields information on the orientation of the fiber strands. Terahertz spectroscopy provides insights into the molecular dynamics of liquid crystals, and reveals semiconductor parameters such as conductivity and carrier density.

A vibrant field of research involves metamaterials, such as sub-wavelength gratings or split-ring resonators which exhibit remarkable transmission characteristics, often with narrow signatures. Depending on the design, the resonance frequency changes when the sample is loaded, e.g. with biological probes. The excellent frequency resolution that cw-terahertz systems deliver provides an extra benefit for these studies.