图案化石墨烯/氮化镓复合超表面对太赫兹波在狄拉克点的动态多维调制

Terahertz dynamic multidimensional modulation at Dirac point based on patterned graphene/gallium nitride hybridized with metasurfaces

提出一种基于图案化石墨烯/氮化镓肖特基二极管与类电磁诱导透明超表面集成的新型太赫兹调制器.通过施加连续激光或偏置电压改变异质结肖特基势垒,进而致使石墨烯的费米能级在价带、狄拉克点与导带之间移动,使得异质结的电导率发生变化.在太赫兹时域光谱上表现出透射振幅的增减变化,并观察到在狄拉克点上的调制行为.因费米能级接近狄拉克点,对外加光电激励非常敏感,施加4.9-162.4 mW/cm^(2)的光功率或者0.5-7.0 V的偏压,调制深度先增加后减小,相位差线性增加,其中最大调制深度达90%,最大相位差为189°,该器件实现了太赫兹波的超灵敏多维动态调制.总之,该图案化石墨烯/氮化镓复合超表面调制器在超灵敏光学设备中存在潜在的应用价值.

The development of terahertz(THz)technology is creating a demand for devices that can modulate THz beams.Here,we propose a novel THz modulator based on patterned graphene/gallium nitride Schottky diodes hybridized with metasurfaces.Ultrasensitive dynamic multidimensional THz modulation is achieved by changing the Schottky barrier of the heterojunction,shifting the Fermi level between the Dirac point,changing the conduction band and the valence of graphene via continuous-wave optical illumination or bias voltages.When the Fermi level is close to the Dirac point,the modulation is ultrasensitive to the external stimuli.Applying an optical power of 4.9–162.4 mW/cm^(2) or a bias voltage of 0.5–7.0 V,the modulation depth initially increases,then decreases,and the phase difference linearly increases,therein the maximum modulation depth is 90%,and the maximum phase difference is 189°.In short,the proposed THz modulator has potential application in ultra-sensitive optical devices.