ph5b00317_si_001pdf. (870.12 kB)
Integrated Terahertz Graphene Modulator with 100% Modulation Depth
Version 2 2015-12-17, 10:42
Version 1 2015-11-18, 14:25
journal contribution
posted on 2015-12-17, 10:42 authored by Guozhen Liang, Xiaonan Hu, Xuechao Yu, Youde Shen, Lianhe
H. Li, Alexander Giles Davies, Edmund H. Linfield, Hou Kun Liang, Ying Zhang, Siu Fung Yu, Qi Jie WangTerahertz
(THz) frequency technology has many potential applications in nondestructive
imaging, spectroscopic sensing, and high-bit-rate free-space communications,
with an optical modulator being a key component. However, it has proved
challenging to achieve high-speed modulation with a high modulation
depth across a broad bandwidth of THz frequencies. Here, we demonstrate
that a monolithically integrated graphene modulator can efficiently
modulate the light intensity of the THz radiation from a THz quantum
cascade laser with a 100% modulation depth for certain region of the
pumping current, as a result of the strongly enhanced interaction
between the laser field and the graphene enabled by this integration
scheme. Moreover, the small area of the resulting device in comparison
to existing THz modulators enables a faster modulation speed, greater
than 100 MHz, which can be further improved through optimized designs
of the laser cavity and modulator architectures. Furthermore, as the
graphene absorption spectrum is broadband in nature, our integration
scheme can be readily scaled to other wavelength regions, such as
the mid-infrared, and applied to a broad range of other optoelectronic
devices.