Active Bidirectional Precise Time Transmission Outside the Telecommunication Bands Over 200 km of Single Mode Fiber

Precise time and/or stable optical frequency transfers over fiber are more and more deployed presently. Parallel transmission with telecommunication signals is often necessary, especially due to high intercity fiber rental costs. This parallel telecommunication traffic often exhaust both low loss transmission windows in single mode fibers (Conventional and Long, together 1530-1610 nm) where mature Erbium Doped Fiber Amplifiers are available. And very typically some additional spectral guard-bands are required. In our contribution we present results of fully bidirectional precise time transmission, over 1460 nm window with low attenuation penalty using modern fibers. Optical clock based on single calcium ion trapped into laser trap are being developed by different groups. Transition of interest for this optical clock corresponds to wavelength of 729 nm which can be down-converted into wavelength of 1458 nm without necessity of using an optical comb. In this paper, we experimentally verify time and radio frequency transmission using White Rabbit system operating in 1470 nm band over 200 km of standard single mode fiber and over more than 50 dB of attenuation using commercially available semiconductor optical amplifier.