January 11, 2023
Keio University
RIKEN
Assistant Professor Shun Fujii of the Department of Physics, Faculty of Science and Technology, Keio University, has developed a method for the continuous and wide-range control of an ultra-high repetition rate optical frequency comb (microcomb) exceeding 20 GHz, generated using a high-Q single-crystal microresonator. This was achieved in collaboration with a research group from the same university, including Professor Takasumi Tanabe and Technical Staff Motoi Kumazaki of the Department of Electronics and Electrical Engineering, and Koshiro Wada (at the time of the research), Ryo Kanno, and Soma Kogure from the Master's Program at the Graduate School of Science and Technology, as well as Team Leader Yuichiro Kato (principal investigator at the RIKEN Pioneering Research) of the RIKEN Center for Advanced Photonics.
Optical frequency combs generated using high-Q microresonators with diameters of a few millimeters or less are called microcombs. They are anticipated to have numerous applications as next-generation optical frequency comb sources capable of compact and energy-efficient operation. However, a challenge has been the difficulty in precisely controlling their performance due to the small size of the resonator element that acts as an oscillator. This study demonstrates that by effectively utilizing high-speed optical frequency control technology with a feedback circuit and the intrinsic thermal properties of the resonator material, the optical spectrum and output power of the microcomb can be precisely tuned over a wide range. This achievement is expected to serve as an important guideline for future applications in precision spectroscopy and low-noise microwave sources.
The results of this research were published in the online edition of the British scientific journal Communications Physics on January 10, 2023 (JST).
Please see below for the full press release.