Probing negative refractive index of metamaterials by terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy (THz-TDS) offers a new perspective for extraction of negative refractive index of low-loss metamaterials directly. We present the detailed extraction procedure how to obtain the negative refractive index of metamaterials through THz-TDS measurement. The basic equations are deduced to obtain the negative index through comparison of THz data measured for the sample and reference, respectively. Further simulation examples matching the practical experimental cases are given, which verifies that the extraction procedure is reliable. This approach demonstrates the potential use of THz-TDS in study of metamaterials and is helpful for design of metamaterial devices.