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.

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