Bidirectional erbium-doped fiber amplifiers used in joint frequency and time transfer based on wavelength-division multiplexing technology

In an experiment on the round-trip fiber transfer of joint frequency and time signals based on wavelengthdivision multiplexing technology, a specific bidirectional erbium-doped fiber amplifier (Bi-EDFA) with low noise and high symmetry simultaneously is designed and applied to compensate for the loss of the link.The Allan deviation (ADEV) deterioration of the 1 GHz frequency signal induced by the Bi-EDFA is only 8 × 10 -15 at 1 s and 9 × 10 -18 at 10 4 s in the forward direction, and is 1.7 × 10 -14 at 1 s and 1.2 × 10 -17 at 10 4 s in the backward direction.The degraded time deviation (TDEV) caused by the asymmetry of the Bi-EDFA is only 0.8 ps at an average time of 10 3 s.With the proposed Bi-EDFA, in the field experiment on the 110 km fiber transfer of joint frequency and time signals, the ADEV of the 1 GHz frequency signal is 7.3 × 10 -14 at 1 s and 2.5 × 10 -17 at 10 4 s.The TDEV of the 1 pulse per second time signal is 6.8 ps with an average time of 10 3 s.