Terahertz optical material based on wood-plastic composites

We investigated the terahertz optical properties of wood-plastic composites (WPCs) having varying wood powder contents. To evaluate the influence of water uptake, we measured WPC samples under conditions where the water content of each WPC sample was controlled. We found that the refractive indexes and the absorption coefficients of the WPCs increased with accumulating wood powder content. Also, we found that the optical properties of the WPCs were almost constant for wood powder contents ranging from 0 wt% to 40 wt%, even in a high-humidity environment. WPCs are promising materials for terahertz optical components.