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在太赫兹通信等系统中需要利用太赫兹波调制器对信号进行调制。基于Ga As等传统半导体材料设计和制作的调制器在太赫兹波段的响应过低,因而很难应用于太赫兹系统。为了弥补传统调制技术在带宽和调制深度不够的缺点,设计了一种全新的基于硅基石墨烯的全光控太赫兹强度调制系统。该调制系统利用材料中光生载流子对太赫兹波的吸收特性,通过调节照射到材料上的可见光光强来改变光生载流子浓度,从而实现对太赫兹波强度调制。从理论和实验两方面对这种新型太赫兹强度调制系统的调制深度和调制带宽进行了研究。研究结果表明,在泵浦光功率密度为18 m W/mm2时,该调制系统能在实验使用的THz-TDS测试系统(0.1~2.5 THz)的整个频谱范围内进行有效的调制,调制深度可达到12%。且随着泵浦光能量的增大,调制深度增大。
In terahertz systems, terahertz wave modulators are needed to modulate the signals. Modulators designed and fabricated on traditional semiconductor materials such as GaAs have too little response in the terahertz band, making them difficult to apply to terahertz systems. In order to compensate for the shortcomings of traditional modulation techniques in terms of bandwidth and modulation depth, a new all-optical terahertz intensity modulation system based on graphene based on silicon is designed. The modulation system utilizes the absorption of terahertz waves by photogenerated carriers in the material and changes the photo-generated carrier concentration by adjusting the light intensity of the visible light irradiated on the material so as to modulate the intensity of the terahertz wave. The modulation depth and modulation bandwidth of this new THz intensity modulation system are studied theoretically and experimentally. The results show that the modulation system can be effectively modulated over the entire spectral range of the experimental THz-TDS test system (0.1 to 2.5 THz) at pump power densities of 18 mW / mm2, with modulation depth Reached 12%. And with the pump light energy increases, the modulation depth increases.