Joint time and frequency transfer through one International Telecommunication Union 100 GHz wavelength division multiplexing channel with commercial devices.

We proposed a joint time and frequency transfer scheme over a single International Telecommunication Union 100 GHz wavelength division multiplexing (WDM) channel using a normal commercial WDM device and commercial offset WDM device. A standard 100 GHz WDM channel is divided into three sub-channels with a frequency interval of more than 20 GHz for a time and frequency transfer, which could help to avoid the interference among time, frequency, and data signals in other WDM channels. A joint high-precision time and frequency transfer is, therefore, able to be performed with data transmission over WDM optical communication links without extra requirements on devices. A joint time and frequency transfer in a single 100 GHz WDM channel is experimentally demonstrated over a 60 km fiber link with the communication data transmission in the adjacent channels. The stability of the time transfer can be better than 15 ps at 1 s, and the stability of the frequency transfer can be better than 2.7×10 at 1 s, while the bit error rates of the adjacent channels are at the same level as the separate transmission.