Broadband electrically controlled bismuth nanofilm THz modulator
Qi Song, Hao Chen, Min Zhang, Ling Li, Junbo Yang, Peiguang Yan
Abstract
In order to greatly promote impressive applications in terahertz (THz) photonics, research on active optoelectronic THz devices with high performance such as modulators is still a vital work. Electrically controlled THz modulators with a large modulation depth and wide modulation bandwidth are urgently needed for THz technology. Herein, a bismuth (Bi) nanofilm is rationally designed as an electrically controlled THz modulator combining the advantages of high electron mobility and near zero bandgap. The Bi nanofilm devices are produced by the magnetron sputtering deposition method, and the maximum modulation depth reaches 70% in the transmission spectrum. We have demonstrated an electrically tunable Bi nanofilm of modulating THz waves dynamically. Moreover, the Bi nanofilm modulator exhibits broadband modulation performance within a wide frequency range from 0.1 to 1.1 THz. Taking advantage of the excellent modulation property and simple approach to design, semimetal based devices are promising components for the development of high performance THz applications.