Abstract-Active control of terahertz plasmon-induced transparency in the hybrid metamaterial/monolayer MoS2/Si structure

Jie Ji,  Siyan Zhou,  Weijun Wang,  Furi Ling,  Jianquan Yao

https://pubs.rsc.org/en/Content/ArticleLanding/2019/NR/C8NR08813F#!divAbstract

Active control of terahertz wave is critical to the development of terahertz devices. Two dimensional materials with excellent optical properties provide more choices for opto-electrical devices with the maturity of their preparation technology. We proposed a hybrid structure of metamaterial/monolayer MoS2/Si and investigated its optical properties in terahertz range. The phenomenon of the plasmon-induced transparency (PIT) effect was observed in the transmission spectra, resulting from near-field coupling of two bright modes. According to simulated results, the phenomenon was confirmed its dependency on the length of the cutwire and distance between DSSRs. Furthermore, an external optical field supported by a 1064 nm laser could realized a switch effect on the sample. The resonances of the PIT metamaterial was disappeared when the optical power was further increased, as excited carriers in MoS2/Si substrate blocked the coupling effect. In addition, experimental results inferred that the PIT metamaterial enhanced the interaction of infrared light with monolayer MoS2/Si substrate.

Abstract-Tunable characteristics of the SWCNTs thin film modulator in the THz region

Weijun Wang, Wen Xiong, Jie Ji, Yue Tian, Furi Ling, and Jianquan Yao

Fig. 1 200 nm high interdigitated electrodes grown on silicon substrate.

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-9-4-1776

The modulation characteristics of the polyimide-based film of SWCNTs at room temperature were studied with time-domain terahertz (THz) spectroscopy in the study. The transmission greatly reduced with an increase in the power of the external optical pump. Under the pump power of 300 mW, the transmission even decreased to 3.4% of that of the original SWCNTs sample without illumination. The modulation depth of the film reached 95.6% at 300 mW, indicating the excellent modulation effect. In addition, the optical pump greatly increased the conductivity and caused a blue shift in the real conductivity peak. In order to explore the electric field modulation characteristic of the polyimide-based SWCNTs film, the results of the conductivity at 0 mW and 300 mW under different voltages were discussed. The change in transmission at 300 mW was much more significant than that at 0 mW, indicating that the modulation effect of voltage was more obvious under the condition of illumination. However, even under the pump power of 300 mW, the modulation depth was only 41.11% at 0.7 THz. In terms of the modulation depth of the optic field and electric field, we believed that the optical modulator worked better for the polyimide-based SWCNTs film.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Active multifunctional terahertz modulator based on plasmonic metasurface

Jie Ji, Siyan Zhou, Weijun Wang, Chunya Luo, Yong Liu, Furi Ling, and Jianquan Yao

Fig. 1 (a) The schematic of an efficient light modulator based on a frequency-selective tunable terahertz metasurface. The sample size was 15 mm*15mm. (b) the OM image of the sample when the photo-resist was lift off. (c) Geometry of the unit-cell of the metasurface with parameters: L1 = 120 um, L2 = 80 um, h1 = 30 um, h2 = 25 um, a = 30 um, g = w = 5um. Metal thickness for the metasurface: d = 100 nm (5 nm Ti + 95 nm Al).

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-27-3-2363&id=404331

An active multifunctional terahertz modulator based on plasmon-induced transparency (PIT) metasurface under the effect of external infrared light was investigated theoretically and experimentally. A distinct transparency window, which resulted from the near-field coupling between two resonators, could be observed in the transmission spectra. Experimental results showed a phenomenon infrared light induced blue shift on the both resonator with increasing optical powers. When the optical power was tuned from 0 mW to 400 mW, the amplitude tunability of transmission at transparency window reached to 34.01%, much larger than that at the two resonance frequencies. Moreover, the phase tunability of the transmission at 0.98 THz reached to 31.35%. Meanwhile, the amplitude variation was limited to 10%. Furthermore, a coupled Lorentz oscillator model was adopted to analyze the near-field interaction of the resonances. Experimental results were in good agreement with the analytical fitting results.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement