研究了锗基单层石墨烯结构宽带光控太赫兹调制器。利用实验室搭建的太赫兹时域光谱系统, 实验证明了在1 550 nm 飞秒光泵浦下, 该太赫兹调制器工作带宽为0.2~1.5 THz。当泵浦光功率从0增加到250 mW时, 该太赫兹波调制器的平均透过率从40%下降到22%, 平均吸收系数从19 cm-1增加到44 cm-1, 在0.2~0.7 THz, 调制深度均高于50%, 最大调制深度为62%(0.38 THz)。实验结果表明, 相比于纯锗基太赫兹调制器, 单层石墨烯的引入能增强对太赫兹波的调制效果。

A spectrally wide-band terahertz modulator based on monolayer graphene on germanium (GOG) was proposed. Utilizing a homemade THz-TDS (Terahertz-time domain spectroscopy) system, it was experimentally demonstrated that the THz modulator can be tuned by a 1 550 nm pump beam in a frequency range from 0.2 to 1.5 THz. The average transmittance of THz decreased from 40% to 22% when the pump power was increased to 250 mW, while the absorption coefficient averaged increased from 19 to 44 cm-1. The maximum modulation depth of the GOG modulator can reach as high as 62% at 0.38 THz and in a frequency range from 0.2 to 0.7 THz, the modulation depth was over 50%. Compared with bare Ge, it was proved that the modulation performance can be moderately enhanced by introducing monolayer graphene. This novel optically controlled graphene based THz modulator provides a feasible method for terahertz applications in communication and imaging.