Fig. 1. Link model of WR system. (a) Schematic diagram of WR system, (b) delay model of WR system. ΔTXM, ΔRXM are the transmission and reception delays of the master device. ΔTXS, ΔRXS are the transmission and reception delays of the slave device. εM, εS are the bitslide values while aligning the received data stream. δMS, δSM are the one-way propagation latencies in fiber. WDM, wavelength division multiplexer; CDR, clock data recovery circuits.

Fig. 2. (a) Schematic diagram of the proposed WR synchronization method. (b) The delay model of the proposed WR link. tTXM, tRXM, tTXS, and tRXS are the transmission delays in fiber circulators.

Fig. 3. (Color online) Result of two synchronization schemes. (a) Time deviation of the proposed method when the WR master and slave are connect directly. (b) Time deviation of the conventional method when the WR master and slave are connect by a 3-m-long fiber.

Fig. 4. (Color online) Result of two schemes when the WR master and slave are connected by a 5 km fiber.

Fig. 5. (Color online) Result of two schemes when the WR master and slave are connected by a 50 km fiber.