Linear dichroism and birefringence spectra of bamboo and its use as a wave plate in the terahertz frequency region

Abstract

The applications of terahertz (THz) waves have been increasing rapidly in various fields, and there is a strong demand for efficient, robust, and low-cost optical components working in the terahertz frequency region. Bamboo, being one of the naturally occurring renewable resources, it has the potential to be used as an easily accessible and sustainable material for the fabrication of terahertz optical components. In this article, transmission mode terahertz time domain spectroscopy (THz-TDS) is used to investigate the terahertz properties, such as refractive index and absorption coefficient of three different species of bamboo in a frequency range from 200 GHz to 1 THz. Remarkable features such as birefringence and linear dichroism are observed, and the origin of these properties is primarily attributed to the orientation of fiber in the bamboo. The possibility of fabricating waveplates using bamboo is explored, and a quarter waveplate working in the sub-terahertz frequency region is demonstrated as a proof-of-principle. This wave plate can be used in terahertz sensing and imaging systems.