April 28, 2022
Research Center for Advanced Science and Technology, The University of Tokyo
Electromagnetic Materials Research Institute
Keio University
Japan Science and Technology Agency (JST)
It is known that topological optical waveguides that transmit light in only one direction can be realized by utilizing special light states called chiral edge states. Because these waveguides can transmit light without scattering or reflection even in the presence of structural fluctuations or defects that occur during fabrication, they are expected to enable higher density and higher functionality in photonic integrated circuits used for optical wiring and other applications. However, it has been considered difficult to make topological optical waveguides that utilize these chiral edge states function over a wide wavelength range in the optical communication wavelength region, which is the main operating wavelength of photonic integrated circuits.
A research group led by Project Assistant Professor Tianji Liu (at the time of the research) and Professor Satoshi Iwamoto of the Research Center for Advanced Science and Technology at the University of Tokyo, Associate Professor Yasutomo Ota of Keio University, and Chief Researcher Shinsei Kobayashi and principal investigator Kenji Ikeda of the Electromagnetic Materials Research Institute focused on the structure of photonic crystals containing a magneto-optical material (a material that exhibits the magneto-optical effect) with a characteristic called epsilon-near-zero (ENZ), where the permittivity is close to zero, and conducted numerical analysis. The results revealed that by using a magneto-optical material with ENZ properties, it is possible to realize a broadband topological waveguide that can operate over a wavelength band more than 1000 times wider than previously reported.
This achievement opens up the possibility of topology-based photonic integrated devices, such as unidirectional waveguides, which have been difficult to realize with conventional technology. It is expected to contribute to higher efficiency and functionality in various applications based on integrated optical circuit technology.
This research was published online in the American scientific journal "ACS Photonics" on April 27, 2022 (Pacific Daylight Time).
This research was supported by the JST CREST program "Creation of Topological Integrated Optical Devices" (JPMJCR19T1), Grant-in-Aid for Scientific Research (S) (17H06138), Grants-in-Aid for Scientific Research (C) (17K06849, 19K05300), Grant-in-Aid for Challenging Research (Exploratory) (19K21959), and the Nippon Sheet Glass Foundation for Materials Science and Engineering.
Please see below for the full press release.