High-Speed and Broadband Terahertz Wave Modulators Based on Large-Area Graphene Field-Effect Transistors

Qi-Ye Wen, Qi Mao, wee tian, Tian-Long Wen, Zhi Chen, Qing-Hui Yang, and Huaiwu ZHANG

Abstract

We present a broadband terahertz wave modulator with large modulation depth and fast switch speed by cautiously selecting the gate dielectric materials in a large-area graphene field-effect transistor (GFET). An ultrathin Al2O3 film (~60 nm) is deposited by atomic-layer-deposition technique as a high-ĸ gate dielectric layer, which reduces the Coulomb impurity scattering and cavity effect thus greatly improves the modulation performance. Our modulator has achieved a high modulation depth of 22 % and modulation speed of 170 kHz in a frequency range from 0.4 to 1.5 THz, which is vital for many THz technology applications as well as for fundamental researches.

This study was performed using TeraView's Spectra 3000 system. (TeraView, Cambridge, UK)

Full Article: http://www.opticsinfobase.org/ol/upcoming_pdf.cfm?id=216913