Terahertz frequency reference transfer via an optical fiber link

Transfer of Terahertz frequency reference via an optical fiber link was demonstrated. Utilizing a Brillouin scattering phenomenon of a long optical fiber link, only two optical modes of an optical frequency comb whose spectra broaden over 10THz are selectively amplified and transmitted. By photomixing the transmitted optical lights a THz frequency reference is generated at the end of the fiber link. We transmitted a 100GHz reference via a 50km spooled fiber, a 1km actually-laid fiber link and a 90km Tokyo urban fiber link, and evaluated their degradations due to the transmission.