Department of Electrical Engineering, University of Southern California, Los Angeles, California, CA 90089, USA.
Department of Chemistry, University of Southern California, Los Angeles, California, CA 90089, USA.
Nanoscale. 2017 Jan 26;9(4):1721-1726. doi: 10.1039/c6nr07054j.
We report a terahertz optical modulator consisting of randomly stacked trilayer graphene (TLG) deposited on an oxidized silicon substrate by means of THz-Time Domain Spectroscopy (THz-TDS). Here, the gate tuning of the Fermi level of the TLG provides the fundamental basis for the modulation of THz transmission. We measured a 15% change in the THz transmission of this device over a broad frequency range (0.6-1.6 THz). We also observed a strong absorption >80% in the time-domain signals and a frequency independence of the conductivity. Furthermore, unlike previous studies, we find that the underlying silicon substrate, which serves as a gate electrode for the graphene, also exhibits substantial modulation of the transmitted THz radiation under applied voltage biases.
我们报告了一种太赫兹光调制器，它由随机堆叠的三层石墨烯（TLG）组成，通过太赫兹时域光谱（THz-TDS）沉积在氧化硅衬底上。在这里，TLG 的费米能级的栅极调谐为太赫兹传输的调制提供了基本依据。我们在较宽的频率范围内（0.6-1.6 THz）测量了该器件的太赫兹传输变化 15%。我们还在时域信号中观察到>80%的强吸收和电导率的频率独立性。此外，与先前的研究不同，我们发现作为石墨烯栅极的底层硅衬底在施加电压偏置时也会对透射太赫兹辐射进行大幅度调制。
