Femtosecond laser optical comb-based ultra-precision generation of optical frequencies of hundreds of terahertz (stability of 1.0 Hz) and its transfer through free space
The research team led by Prof. KIM, Seung-Woo and Prof. KIM, Young-Jin at the Department of Mechanical Engineering of KAIST developed multi-channel optical frequency ultra-precision transfer technology that allowed for optical frequency transfer with a stability of 1 Hz while at the same time perfectly reconstructing the optical phase; by transferring 193-THz femtosecond laser optical combs (including millions of optical frequencies) with excellent stability of a thousand-trillionth, or 1/1,000,000,000,000,000, over an 18 km open-air link and precisely measuring and controlling how the optical frequencies and phases of these optical combs were affected while passing through the atmosphere. It is expected that this technology will innovatively improve the speed and energy efficiency limits of existing space-to-ground communications technology using microwaves; contribute to attempts to develop next-generation navigation devices and secure original technologies involved in space measurement by allowing for ultra-precision space-to-ground time/frequency transfer; and enhance the utility of inter-country and inter-continent ultra-precision time/frequency comparison and transfer, which has only been implemented through optical fibers to date. The research results above were published in Nature Communications on September 30 in recognition of their excellence.
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