May 14, 2024
Keio University
A research group from Keio University—led by Assistant Professor Shun Fujii of the Department of Physics, Faculty of Science and Technology; Professor Takasumi Tanabe of the Department of Electronics and Electrical Engineering; Motoi Kumazaki, a technical staff member at the same faculty; and Koshiro Wada and Soma Kogure, who were master's students at the Graduate School of Science and Technology at the time of the research—has succeeded in generating an optical frequency comb with a very high repetition rate of about 15 GHz by applying minute mechanical pressure using a piezoelectric element. This research is expected to make a significant contribution to the future application of high-speed, high-capacity communications, microwave radar, and optical clocks.
Optical frequency combs generated using high-Q micro-optical resonators are called microcombs. Due to their high repetition rates and integrability, various applications have been proposed for them as next-generation optical frequency comb light sources. While the generation of microcombs generally requires precise wavelength control of a high-performance laser, this research group has demonstrated that by simply applying minute mechanical pressure to an optical resonator made of a single crystal, it is possible to generate a mode-locked microcomb, known as a soliton comb, and precisely control its repetition rate without needing to control the pump laser.
This method is expected to dramatically improve the performance of high-repetition-rate microcombs. Furthermore, this is a significant result that can greatly contribute to the miniaturization and cost reduction of microcomb devices for future market deployment.
This research was published in the German online scientific journal "Laser & Photonics Reviews" on April 24, 2024 (JST).
Please see below for the full press release.