February 16, 2022
Keio University
Professor Hideyuki Maki and his research group at the Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, have realized a high-performance optical switch on a silicon chip by integrating a microheater using graphene, a carbon material as thin as a single atom, with silicon photonics. This technology is expected to be applied to new on-chip optical devices, such as for high-speed switching of communication paths in optical communications, as well as for optical integrated circuits and optical quantum information chips integrated on silicon chips.
An optical switch is a device that directly switches the path of an optical signal without converting it into an electrical signal. In optical communications, it is a crucial component supporting high-speed communication, used for tasks such as switching the communication paths that transfer data. While various types of optical switches are currently being developed, optical switches using optical waveguides integrated on silicon chips are attracting attention as next-generation, highly integrated, and compact devices. In this approach, the mainstream devices are optical switches that operate based on the thermo-optic effect, which changes the refractive index through heating by a heater. However, with current metal heaters, limitations in improving performance, such as switching speed and efficiency, have been a challenge.
This time, we have developed a new optical switch by directly forming a graphene microheater on a silicon photonics device, using graphene with its superior thermal properties as a replacement for conventional metals. As a result, performance was significantly improved even in an optical switch with a device structure similar to that of conventional metal heaters, achieving an extremely fast optical switch with a response time of a few microseconds. This technology has shown that graphene, a two-dimensional material, is extremely promising as a material for optical switches in silicon photonics. In the future, it is expected to be applied to various on-chip integrated optical device technologies, such as next-generation high-capacity optical communication chips, optical interconnects, optical integrated circuits, and quantum information chips.
This research was conducted in collaboration with Associate Professor Yasuaki Monnai of the Research Center for Advanced Science and Technology, The University of Tokyo (at the time of the research, he was with the Faculty of Science and Technology, Keio University).
The results of this research were published in the online edition of *ACS Nano* by the American Chemical Society (ACS) on February 14, 2022.
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