Transmission properties of terahertz metamaterial fabricated on isotropic and anisotropic substrate

摘要

Resonance and absorption peak of transmission spectrum can be achieved when terahertz pulses transmit through the split-ring resonators (SRRs). Using the theory of LC oscillating circuit and the model of half wave resonance, we can account for the phenomenon. We once fabricate metal subwavelength dual-ring structure which is different from the SRRs and there aren't splits in. The resonance and absorption peak, however, still appear in the THz frequency range. In this time, we respectively fabricate the dual-ring structure and reverse dual-ring structure on quartz crystal substrate and silicon. When the metal structure is fabricated on quartz crystal, Using terahertz time-domain spectroscopy (TDS), we find the characteristic spectra exist as well as time domain waveform and frequency domain spectra of transmitted terahertz pulses present obviously periodic variation with rotating the sample round the normal of its surface. However, if silicon is used as substrate, the phenomena will not appear. In this article, we will analyze the phenomena and obtain the reason resulting in it. We hold that the metal dual-ring structure in itself can't lead to the variation of the terahertz pulses by changing the sample's angle due to isotropy of the dual-ring structure in surface of the sample. We think the phenomenon may originate from quartz crystal substrate.