Polarization Scramblers to Solve Practical Limitations of Frequency Transfer

Xu, Dan; Lopez, Olivier; Amy‐Klein, Anne; Pottie, Paul-Eric

doi:10.1109/jlt.2021.3057804

Cited by 5 publications

(3 citation statements)

References 32 publications

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“…This could be due to some technical limitations, such as for instance non-optimal parametrization of the SoftPLL and/or the WR engine, mistakes in the phase comparator (that is to say the digital dual mixer time difference meter implemented in the FPGA at heart of the WR engine [67]), or mistakes in the servo loop physical model. It could also be due to an asymmetry in the propagation delay for the forward and backward signal that were not well taken into account in our model, possibly linked to more fundamental reasons such as the effect of temperature on birefringence of the fiber as reported recently in the optical domain with fiber spools [68], [69].…”

Section: Discussionmentioning

confidence: 93%

A 500-km Cascaded White Rabbit Link for High-Performance Frequency Dissemination

Kaur

Frank

Pinto

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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We perform experiments exploring the use of White Rabbit PTP for time and frequency dissemination over longdistance optical fiber links. We use unidirectional links, to ensure compatibility with active telecommunication networks, and White Rabbit equipment with modifications for improved performance. Using fiber spools, we realize a 500 km, four-span cascaded White Rabbit link. We show short term fractional frequency stability of 2 × 10 −12 , averaging down to 2 × 10 −15 at one day of integration time, with no frequency shift within the statistical uncertainty. We demonstrate the impact of increasing the White Rabbit SoftPLL bandwidth and the PTP message rate. We show evidence of the effect of thermal fluctuations acting on the fiber, and finally discuss the limitations of the achieved performance. We show comparisons with experimental data acquired with commercial good quality GPS receivers and show that the medium-and long-term stability and accuracy are more than one order of magnitude better with a White Rabbit PTP link.

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Section: Discussionmentioning

confidence: 93%

A 500-km Cascaded White Rabbit Link for High-Performance Frequency Dissemination

Kaur

Frank

Pinto

et al. 2022

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…However, such a solution cannot work reliably in practice, as standard fibers change their polarization state randomly due to external factors such as temperature and mechanical stress variations [16]. A simple solution may be to use a polarization scrambler [16], [32], which is a standalone fiber-optic component, not requiring any additional feedback loop or control algorithms (in contrast to an adaptive polarization controller). However, the polarization scrambler reduces the average power of the beat by 3 dB, resulting in a modulation of the IF signal level driving the prescaler (see Fig.…”

Section: Penalty Due To Polarization Scramblingmentioning

confidence: 99%

Systematic Frequency Error in Laser Synchronization Circuits for Fiber-Optic Time-Transfer Systems

Śliwczyński

Krehlik

Buczek

et al. 2023

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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The paper addresses the problem of a systematic frequency error occurring in semiconductor-laser frequency-synchronization circuits based on counting the beat note between the two lasers in a reference time interval using a high-frequency prescaler. Such synchronization circuits are suitable for operation in ultra-precise fiber-optic time-transfer links, used e.g. in time/frequency metrology. The error occurs when the power of the light coming from the reference laser, to which the second laser is synchronized, is below about -50 dBm to -40 dBm, depending on the details of particular circuit implementation. The error can reach tens of MHz if left out of consideration and does not depend on the frequency difference between the synchronized lasers. Its sign can be positive or negative, depending on the spectrum of the noise at the prescaler input and the frequency of the measured signal. In the paper we present the background of the systematic frequency error, discuss important parameters allowing for predicting the error value, and describe the simulation and theoretical models being helpful for designing and understanding operation of discussed circuits. The theoretical models presented here show good agreement with the experimental data, which demonstrates the usefulness of proposed methods. Implementing polarization scrambling to mitigate the effect of polarization misalignment of the lights of the lasers used was considered and the resulting penalty was determined.

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“…However, asymmetric transmission spectrum of FRR has been observed in many researches, results in the inability of the laser center frequency to track and lock the resonant frequency of the FRR, thereby seriously affecting system stability [9]. Prior studies have indicated that including polarization fluctuation [10], Kerr effect [11], temperature disturbance [12], and coupler manufacturing error [13]will affect the symmetry of the resonance curve, of which coupler error is the most influential. Classic theoretical model simply define the orthogonal mode loss difference of the coupler as π/2, therefore, it can not This work was supported in part by the National Natural Science Foundation of China under grant 52075131.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Fiber Ring Resonator Transmission Spectrum Based on Multi-Beam Interference Theory and Transfer Matrix Theory

Liu,

Tan,

Cui

2024

IEEE Photonics J.

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Polarization maintaining fiber(PMF) effectively reduces mode splitting and back scattering interference compared to Single Mode Fiber(SMF) in the Fiber Ring Resonator(FRR). In traditional reflection PMF-FRR(RPMF-FRR) structure, classic theoretical model suggests that the orthogonal mode loss difference of the coupler, i.e. the phase difference between the output light field at the cross end and through end of the coupler is π/2, however, in practical research, this angle is often less than π/2, which will generate resonance curve asymmetric and severely exacerbate systems instability centered on PMF-FRR. To address this issue, based on the multi-beam interference theory, this article establishes a new mathematical theoretical model and demonstrate a transmission PMF-FRR(TPMF-FRR) with two couplers, the symmetry error has been dwindle to 0.8%, which is a huge improvement compared to 11% of traditional reflection PMF-FRR(RPMF-FRR). Furthermore, different construction methods of TPMF-FRR were studied through theoretical analysis and experimental verification based on the transfer matrix theory, provide guidance for further optimizing the transmission spectrum. The findings contribute to enhance the system precision centered on FRR.

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Polarization Scramblers to Solve Practical Limitations of Frequency Transfer

Cited by 5 publications

References 32 publications

A 500-km Cascaded White Rabbit Link for High-Performance Frequency Dissemination

A 500-km Cascaded White Rabbit Link for High-Performance Frequency Dissemination

Systematic Frequency Error in Laser Synchronization Circuits for Fiber-Optic Time-Transfer Systems

Optimization of Fiber Ring Resonator Transmission Spectrum Based on Multi-Beam Interference Theory and Transfer Matrix Theory

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