Fiber-optic joint time and frequency transfer with the same wavelength

Abstract

Optical fiber links have demonstrated their ability to transfer the ultra-stable clock signals. In this paper we propose and demonstrate a new scheme to transfer both time and radio frequency with the same wavelength based on coherent demodulation technique. Time signal is encoded as a binary phase-shift keying (BPSK) to the optical carrier using electro optic modulator (EOM) by phase modulation and makes sure the frequency signal free from interference with single pulse. The phase changes caused by the fluctuations of the transfer links are actively cancelled at local site by optical delay lines. Radio frequency with 1GHz and time signal with one pulse per second (1PPS) transmitted over a 110km fiber spools are obtained. The experimental results demonstrate that frequency instabilities of 1.7E-14 at 1s and 5.9E-17 at 10 4 s. Moreover, time interval transfer of 1PPS signal reaches sub-ps stability after 1000s. This scheme offers advantages with respect to reduce the channel in fiber network, and can keep time and frequency signal independent of each other.

Fiber Radio Frequency Transfer Using Bidirectional Frequency Division Multiplexing Dissemination

“…As the outside loop of the system is easily susceptible to the temperature fluctuations, the Allan deviations of the different compensated systems decrease slowly within 10 2 − 10 3 s, which correspond to the sharp bump at the range of 0.001 − 0.003 Hz in Fig. 2 [24].…”

Studying the Double Rayleigh Backscattering Noise Effect on Fiber-Optic Radio Frequency Transfer

“…4, compared with the ECD lasers without the DCFs, the short-term stability of the system with the proper DCFs over the 100 km fiber-optic link has been improved from 4.1 × 10 −13 to 2 × 10 −14 at the integration time of 1s, and the long-term stability has been improved from 1.7 × 10 −16 to 7.9 × 10 −17 at the averaging time of 10,000 s. In comparison with the 100 km free running link, the long-term stability at 10,000 s with the ECD lasers and proper DCFs is improved 3000 times. The stabilities of the system are similar from 200 s to 1,000 s, this part is mainly limited by the influence of the outside loop phase noise introduced by the temperature fluctuations [34]. When the system only employs the fiber lasers, the stabilities of the system achieve 7.2 × 10 −14 at 1 s and 1 × 10 −16 at 10,000 s, are a factor of 3 worse than the system with the ECD lasers and the proper DCFs, illustrating that the DBR has a significant effect on fiber-optic radio frequency transfer.…”

A Low Temperature Coefficient Time-to-Digital Converter with 1.3 ps Resolution Implemented in a 28 nm FPGA

“…Accurate time interval measurement is applied in high precision time synchronization, optical sensing and many scientific applications. High-precision optical fiber time-frequency transmission and synchronization technology is the most accurate time-frequency synchronization technology currently in widescale use in the fields of clock comparison [ 1 , 2 ], radar networking [ 3 ], and basic scientific research [ 4 ]. The time-of-flight (TOF) is measured in Light Detection and Ranging(LiDAR) [ 5 ], optical sensing systems for depth measurement [ 6 ] and so on.…”