Research on the Impact of Optical Fiber Link Delay Fluctuation on Frequency Transfer Stability

Delong, 李得龙 Li; Qingming, 程清明 Cheng; Baofu, 张宝富 Zhang; Lin, 卢麟 Lu; Pingji, 雷平纪 Lei; Xiaoya, 李晓亚 Li

doi:10.3788/lop51.010602

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…It was found that the transfer delay fluctuations caused by the variation of refractive index, the variation of fiber link length, and the drift of laser output wavelength are major factors of reducing the instability of T/F synchronization. [18,19] The main factors that affect the instability, including the intensity noises and transfer delay fluctuation caused by various variations, are given in the above papers, but no systematic analysis in a longdistance fiber-optic synchronization system which signal attenuation is compensated by the high isolation Bi-EDFAs.…”

Section: Introductionmentioning

confidence: 99%

Modeling of cascaded high isolation bidirectional amplification in long-distance fiber-optic time and frequency synchronization system*

Mu¹,

Chen²,

Wang³

et al. 2021

Chinese Phys. B

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We propose a physical model of estimating noise and asymmetry brought by high isolation Bi-directional erbium-doped fiber amplifiers (Bi-EDFAs), no spontaneous lasing even with high gain, in longdistance fiber-optic time and frequency (T/F) synchronization system. It is found that the Rayleigh scattering noise can be suppressed due to the high isolation design, but the amplified spontaneous emission (ASE) noise generated by the high isolation Bi-EDFA and the bidirectional asymmetry of the transmission link caused by the high isolation Bi-EDFA will deteriorate the stability of the system. The calculated results show that under the influence of ASE noise, the frequency instability of a 1200 km system composed of 15 high isolation Bi-EDFAs is 1.773 × 10−13/1 s. And the instability caused by asymmetry is 2.6064 × 10−16/30000–35000 s if the total asymmetric length of the bidirectional link length is 30 m. The intensity noises originating from the laser and detector, the transfer delay fluctuations caused by the variation in ambient temperature and the jitter in laser output wavelength are also studied. The experiment composed of three high isolation Bi-EDFAs is done to confirm the theoretical analysis. In summary, the paper shows that the short-term instability of the T/F synchronization system composed of high isolation Bi-EDFAs is limited by the accumulation of ASE noise of amplifiers and the laser frequency drift, while the long-term instability is limited by the periodic variation in ambient temperature and the asymmetry of the amplifiers. The research results are useful for pointing out the direction to improve the stability of the fiber-optic T/F synchronization system.

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Section: Introductionmentioning

confidence: 99%

Modeling of cascaded high isolation bidirectional amplification in long-distance fiber-optic time and frequency synchronization system*

Mu¹,

Chen²,

Wang³

et al. 2021

Chinese Phys. B

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Research on the impact of temperature variation on stability of optical fiber frequency transfer system

et al. 2022

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High-precision long-haul fiber-optic time transfer between multi stations

Chen¹,

Zhao²,

Zhang³

et al. 2017

Acta Phys. Sin.

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To achieve high-precision fiber-optic time transfer, the method of two-way transmission is usually used. Therefore in this paper we propose to develop a high-precision long-haul fiber-optic time transfer between multi stations by simultaneously transferring the 1 pluse per second signal, time code signal and 10 MHz frequency signal over single fiber with the same wavelength, and adopting the time division multi address (TDMA) as well as the purification and regeneration method at individual station. In this proposal, the equipment at each remote station has its own address, and the equipment at the local station can establish the periodic two-way time transfer with any remote station by using the TDMA method, therefore each remote station is synchronized with the local station. To avoid the superimposed effect of optical noises during propagation in fiber, the optical-electro-optical relay amplifiers are utilized. In the meantime the propagation delay of the fiber link is compensated for at each remote station. With the self-developed engineering prototypes, the experimental verifications are subsequently conducted both in laboratory and real field. In the laboratory, the experimental setup is built by cascading 11 rolls of 50 km-long fiber coils, and locating three monitoring devices at different fiber distances of 50, 300, and 550 km from the local station. The stabilities of the time transfer at these three points are achieved to be 16.7, 16.8, and 18.4 ps in standard deviation, and the time deviations are 1.78, 2.09, and 2.92 ps at an averaging time of 1000 s respectively. In the real field test, a field fiber link of 871.6 km in length is utilized, along which 11 self-developed time-frequency transceivers are set at the cascaded fiber-optic stations. Since only the 11th remote station is co-located at the local station, the performance and the time transfer between the 11th remote station and the local station are measured accurately. The time transfer is experimentally demonstrated with the time standard deviation of 29.8 ps and the time deviations of 3.85 ps/1000 s. The timing uncertainty on the field fiber link is also checked and gives a value of 25.4 ps. To further improve the long-term stability of time transfer, the more accurate thermal control of the lasers used in the system should be adopted to reduce the optical wavelength drift. By compressing the bandwidth of the phase locked loop module in each remote device, the short-term stability of time synchronization can also be better. This proposal can also be extended to the fiber networks with star-shaped and chain-shaped connections. Therefore time synchronization in even larger areas and more stations can be realized.

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Research on the Impact of Optical Fiber Link Delay Fluctuation on Frequency Transfer Stability

Cited by 4 publications

References 5 publications

Modeling of cascaded high isolation bidirectional amplification in long-distance fiber-optic time and frequency synchronization system*

Modeling of cascaded high isolation bidirectional amplification in long-distance fiber-optic time and frequency synchronization system*

Research on the impact of temperature variation on stability of optical fiber frequency transfer system

High-precision long-haul fiber-optic time transfer between multi stations

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