State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductor, Chinese Academy of Sciences, Beijing, 100083, PR China.
School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, PR China.
Nanoscale. 2017 Mar 23;9(12):4082-4089. doi: 10.1039/c6nr08964j.
Frequency conversion with nonlinear electronic components, a common approach for signal processing required in various communication applications, has found its operation bandwidth bottleneck due to the limited carrier mobility of the traditional materials. Meanwhile, fiber-optics communications are playing a significant role in communication services due to their excellent signal transmission properties. However, the transmitted optical signals had to be converted to electrical signals with photodetectors before frequency conversion was performed through conventional electronic devices, which make this conversion system very complex and costly. Hence, to develop a compact device that can achieve the photodetection and frequency conversion functions simultaneously is critical and significative. Here, we have proposed a novel concept for frequency conversion and demonstrated a nonlinear graphene photodetector based frequency converter that performs frequency conversion from optical signals directly. With this new concept, a frequency doubling signal at 4 GHz was obtained from a 2 GHz intensity-modulated optical signal. Moreover, using a 10 MHz intensity-modulated optical signal and another 3 GHz intensity-modulated optical signal, we show the frequency up-conversion to 3 ± 0.01 GHz. In particular, the frequency down-conversion to 100 MHz was achieved successfully by using a 2 GHz intensity-modulated optical signal and another 2.1 GHz intensity-modulated optical signal. Considering the broadband optical absorption, strong saturable absorption, high carrier mobility, and short photogenerated carrier lifetime of the graphene material, graphene photodetectors have the potential to achieve the frequency conversion of millimeter-wave band, which will open promising prospects in the domain of microwave photonics for next-gen communication systems.
利用非线性电子元件进行频率转换是各种通信应用中所需的信号处理的常见方法，但由于传统材料的载流子迁移率有限，其工作带宽已达到瓶颈。与此同时，光纤通信由于其优异的信号传输特性，在通信服务中发挥着重要作用。然而，在进行频率转换之前，传输的光信号必须通过光电探测器转换为电信号，而传统的电子设备则完成这种转换，这使得这种转换系统非常复杂和昂贵。因此，开发一种能够同时实现光电检测和频率转换功能的紧凑型设备至关重要。在这里，我们提出了一种新的频率转换概念，并展示了一种基于非线性石墨烯光电探测器的频率转换器，它可以直接从光信号进行频率转换。利用这一新概念，我们从 2GHz 的强度调制光信号中获得了 4GHz 的倍频信号。此外，我们还利用 10MHz 的强度调制光信号和另一个 3GHz 的强度调制光信号，展示了频率上变频至 3±0.01GHz。特别地，我们成功地利用 2GHz 的强度调制光信号和另一个 2.1GHz 的强度调制光信号实现了频率下变频至 100MHz。考虑到石墨烯材料的宽带光吸收、强饱和吸收、高载流子迁移率和短光生载流子寿命，石墨烯光电探测器有望实现毫米波波段的频率转换，这将为下一代通信系统的微波光子学领域开辟广阔的前景。
