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石墨烯从问世至今,受到了研究者的广泛关注,已经发展为二维材料及其异质结构研究的新前沿。它具有宽光谱范围内恒定吸收[1-2]、极高的载流子迁移率[3]、电可控电导率、与CMOS工艺兼容等诸多优点,被广泛应用于光电子器件领域,其中基于石墨烯的电光调制器是石墨烯在光电子器件领域的重要应用之一。由于石墨烯是一种各向异性的二维材料[4],石墨烯波导中不同导模与石墨烯的重叠程度不同,导致石墨烯调制器具有偏振敏感的缺点。目前多数基于石墨烯的调制器是偏振相关的[5-9],只能在一个单偏振态下工作。随后,文献[10-12]提出了多种结构的石墨烯偏振无关电光调制器,其主要思想是通过改变石墨烯在波导中的相对位置,实现部分石墨烯面能够与水平偏振方向的TE模式相互作用,而另一部分石墨烯面能够与垂直偏振方向的TM模式相互作用。但这些结构复杂,对工艺要求高,不便于集成。
基于上述情况,本文提出了一种倒脊型结构硅基石墨烯电光调制器,通过将石墨烯片以一定角度倾斜放置在硅波导中,使得石墨烯片与入射光在水平和垂直方向上的分量都有较好的重叠效果,实现电光调制器的偏振无关。通过仿真计算了在1.55 μm的工作波长,该器件调制下的TE和TM模式的有效模式参数变化情况,1.5~1.6 μm的工作波长下TE和TM模式消光比及其差异,及该器件3 dB的调制带宽。
Design of Graphene Polarization Independent Electro-Optical Modulator Based on Inverted Ridge Structure
doi: 10.12178/1001-0548.2021081
- Received Date: 2021-03-23
- Rev Recd Date: 2021-04-08
- Available Online: 2021-07-23
- Publish Date: 2021-06-28
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Key words:
- electro-optical modulator /
- extinction ratio /
- graphene /
- polarization independent /
- silicon waveguide
Abstract: Based on the analysis of the principle of polarization independent modulation, a new type of inverted ridge polarization independent electro-optic modulator is proposed, which is inclined to place the graphene sheet in a silicon waveguide at a certain angle. At the wavelength of 1.55 μm, the effective mode parameters of TE and TM modes are the same, and the difference of absorption parameters is very small. In addition, the device can achieve extinction ratio higher than 18 dB for TE and TM modes at wavelengths from 1.5 μm to 1.6 μm, and the difference of extinction ratio is less than 4 dB. The 3 dB modulation bandwidth of the device can reach 123 GHz in ideal state.
Citation: | ZHOU Yong, LIN Rui, LU Rong-guo, LÜ Jiang-bo, SHEN Li-ming, WANG Guang-biao, TAN Meng, LIU Yong. Design of Graphene Polarization Independent Electro-Optical Modulator Based on Inverted Ridge Structure[J]. Journal of University of Electronic Science and Technology of China, 2021, 50(4): 592-597. doi: 10.12178/1001-0548.2021081 |