Nakamura Shoma, Sekiya Kota, Matano Shinichiro, Shimura Yui, Nakade Yuuki, Nakagawa Kenta, Monnai Yasuaki, Maki Hideyuki
Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan.
Kanagawa Institute of Industrial Science and Technology (KISTEC), Ebina 243-0435, Japan.
ACS Nano. 2022 Feb 22;16(2):2690-2698. doi: 10.1021/acsnano.1c09526. Epub 2022 Feb 14.
Graphene is a promising material for producing optical devices because of its optical, electronic, thermal, and mechanical properties. Here, we demonstrated on-chip optical switches equipped with a graphene heater, which exhibited high modulation speed and efficiency. We designed the optimal structure of the optical switch with an add/drop-type racetrack resonator and two output waveguides (the through and drop ports) by the electromagnetic field calculation. We fabricated the optical switch in which the graphene microheater was directly placed on the resonator and directly observed its operation utilizing a near-infrared camera. As observed from the transmission spectra, this device exhibited high wavelength tuning efficiency of 0.24 nm/mW and high heating efficiency of 7.66 K·μm/mW. Further, we measured the real-time high-speed operation at 100 kHz and verified that the graphene-based optical switch achieved high-speed modulation with 10%-90% rise and fall response times, 1.2 and 3.6 μs, respectively, thus confirming that they are significantly faster than typical optical switches that are based on racetrack resonators and metal heaters with response times of ∼100 μs. These graphene-based optical switches on silicon chips with high efficiency and speed are expected to enable high-performance silicon photonics and integrated optoelectronic applications.
由于石墨烯具有光学、电学、热学和机械性能，它是一种很有前景的用于制造光学器件的材料。在此，我们展示了配备石墨烯加热器的片上光学开关，其表现出高调制速度和效率。我们通过电磁场计算，设计了一种带有分插型跑道谐振器和两个输出波导（直通端口和分路端口）的光学开关的最佳结构。我们制造了将石墨烯微型加热器直接放置在谐振器上的光学开关，并利用近红外相机直接观察其工作情况。从传输光谱可以看出，该器件表现出0.24 nm/mW 的高波长调谐效率和7.66 K·μm/mW 的高加热效率。此外，我们在100 kHz 下测量了实时高速运行情况，并验证了基于石墨烯的光学开关实现了高速调制，其上升和下降响应时间分别为1.2 和3.6 μs，上升和下降响应时间分别为10% - 90%，从而证实它们比基于跑道谐振器和金属加热器的典型光学开关快得多，后者的响应时间约为100 μs。这些基于石墨烯的硅基芯片光学开关具有高效率和速度，有望实现高性能的硅光子学和集成光电子应用。
