High-Speed Silicon On-Chip Optical Switch Based on a Graphene Microheater: Applications Anticipated in Next-Generation High-Capacity Optical Communication Technologies, Optical Integrated Circuits, and Quantum Chips
March 11, 2022
By integrating a microheater using the atomically thin material, graphene, with silicon photonics, Professor Hideyuki Maki and his colleagues at the Department of Applied Physics and Physico-Informatics in the Faculty of Science and Technology at Keio University have fabricated a high-performance on-chip optical switch. This technology is expected to have applications for new optical devices on silicon chips such as devices that require high-speed path switching for optical communications, optical integrated circuits, and photonic chips.
An optical switch is a device that can re-route an optical signal without converting it into an electrical signal. In the field of optical communications, they are utilized to select the output port of the optical path and are indispensable in supporting high-speed communications. While at present there are a variety of optical switch types under development, for efficient next-generation compact switches, experts are looking to optical switches that have optical waveguides integrated onto silicon chips. Typical optical switches within this category employ a mechanism which changes the refractive index of a material using the thermo-optic effect. However, current switches that use such metal heaters face limitations in their performance related to speed and efficiency.
This research study focused on fabricating a new type of optical switch that uses graphene, a material known for its thermal properties, instead of conventional metals. The researchers were able to form a graphene-based microheater directly on the silicon photonics device. As a result, even while using the same basic structure of optical switches that employ conventional metal-based heaters, the researchers were able to significantly improve the switches’ performance, drastically shortening the rise and fall response times to a few mere microseconds. This technology has demonstrated that graphene, a two-dimensional material, is extremely promising for optical switches in silicon photonics. It is expected to be applied in various on-chip integrated optical device technologies, including next-generation high-capacity optical communications chips, optical interconnects, optical integrated circuits, and quantum chips, etc.
This research was conducted in collaboration with Associate Professor Yasuaki Monnai (affiliated with the Faculty of Science and Technology at Keio University at the time of this study) of the Research Center for Advanced Science and Technology (RCAST) at the University of Tokyo.
The results of this research were published in the online edition of ACS Nano of the American Chemical Society (ACS) on February 14, 2022.
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