June 11, 2020
Keio University
A research group led by Shun Fujii (a third-year student in the Doctoral Programs at the Graduate School of Science and Technology, Keio University, and a JSPS Research Fellow DC1) and Professor Takasumi Tanabe of the Department of Electronics and Electrical Engineering, Faculty of Science and Technology, in collaboration with Professor Yasuhiro Kakinuma and his colleagues at the Department of System Design Engineering, Faculty of Science and Technology, has fabricated a micro-optical device using only ultra-precision cutting, achieving the world's highest optical performance (a Q -factor of 140 million) for a single-crystal microresonator fabricated using a top-down approach.
Optical microresonators confine light in a small area to enhance light-matter interactions. They are used for applications such as optical frequency comb generation, high-sensitivity sensing, and quantum optics, and are being actively researched and developed worldwide. For optical resonators made of fluoride crystals, which are suitable for achieving high light confinement performance ( Q -factor), conventional nanofabrication techniques like those used in semiconductor processing cannot be applied. Therefore, it has only been possible to fabricate devices with limited shapes through polishing. This research applies ultra-precision machining technology to the fabrication of nanophotonic devices, achieving both a high Q -factor and precise structural design in a single-crystal microresonator, which was not possible with conventional methods.
The results of this research will be published in Optica, a journal of The Optical Society (OSA), on June 11, 2020 (JST).
For the full press release, please see below.