Polarization Mode Dispersion Measurement Research Articles

Vector distribution measurement of PMD in optical fiber links employing a wavelength-tunable SOP-OTDR.

A measurement of polarization mode dispersion (PMD) vector distribution is implemented with a wavelength-tunable state-of-polarization-detection-based optical time domain reflectometry (SOP-OTDR). Derived from the dynamic equation between the PMD vector and the birefringence vector with a piecewise approximation method, we present an equation for piecewise expression of the relation between the two vectors based on the approximation that the second-order partial derivative of the PMD vector with respect to the length is negligible in each short-enough segment of optical fiber. Utilizing the birefringence vector distributions at three adjacent wavelengths, both the magnitude and the direction distributions of the PMD vector have been calculated through the numerical solution algorithm. The calculation results indicate that the measured magnitudes of PMD vectors are consistent with the statistical experience, which is the Maxwell probability distribution, and the second-order partial derivative magnitudes of the PMD vectors conform to the lognormal distribution. This method could provide a distributed approach for optical performance monitoring by PMD-related characteristics in optical fiber links.

Polarization mode dispersion measurement using fixed analyzer method with deep neural network

Abstract A fixed analyzer method with deep neural network (DNN) for polarization mode dispersion (PMD) measurement was proposed. The DNN is used to extract the mean differential group delay from the fluctuated power spectrum. The effectiveness of the proposed scheme was demonstrated by experiments. Experimental results show that it is a practical method with greater stability and superior accuracy than counting extrema points method.

基于经验模态分解的偏振模色散测量实验研究

基于经验模态分解的偏振模色散测量实验研究

基于小波阈值去噪的偏振模色散测量

基于小波阈值去噪的偏振模色散测量

Polarization effects in KAT-7 telescope optical fibre network: Towards the distribution of frequency and timing references in the MeerKAT telescope

Polarization mode dispersion (PMD) is one of the key effects in optical fibre communication that distorts the transmitted signal. The effect of birefringence on the polarization states of an optical signal leads to broadening of the pulses in an optical fibre. The difference in propagation time of the orthogonal modes in a fibre results in differential group delay (DGD). For proper functioning of a telescope, accurate and stable clock signals will be distributed via an optical fibre network to each of the dishes. This paper presents field PMD measurement that is essential in estimating the expected phase change of the clock signal. The average DGD of a 10.2km fibre link established to be about 62.1fs. This study serves to address the applicability of optical fibre network transmission in the distribution of frequency and timing reference signals in the MeerKAT and later phases of the square kilometre array (SKA) telescope.

Measurements of polarization mode dispersion on aerial optical cables: Theory and experiments

Higher bit-rate transmission is attractive for improving network resource efficiency and reducing the complexity of network management in future transmission systems. However, chromatic dispersion and Polarization Mode Dispersion (PMD) are one of the most serious impairments. In particular, PMD changes rapidly according to environmental variations such as temperature change and mechanical vibration. This study presents PMD measurements in a mixed aerial and buried optical longhaul network. PMD was measured as a part of a thorough analysis, in order to assess the possibility of deploying, in this actual route, a DWDM network based on 10Gb/s and 40 Gb/s carriers long haul network based on DWDM technology PMD was measured as a part of the previous analysis, in order to assess the possibility of deploying routes based on 10Gb/s carriers and on 40Gb/s carriers. Changes of PMD were mainly introduced by external factors (such as temperature), but also by changes in the wind speed that significantly contributed to changes in Differential Group Delay (DGD), causing side-effects such as bending, transverse pressure or twists on the fiber hauls. In this study we will focus on the effects over PMD caused by the wind speed and its relevant impact on the aerial hauls, where the influence is significant. A quantitative comparison between data obtained from real measurements and data obtained from analytical approaches will be established.

Evaluation of polarization mode dispersion in a telecommunication wavelength selective switch using quantum interferometry

A polarization mode dispersion (PMD) measurement of a commercial telecommunication wavelength selective switch (WSS) using a quantum interferometric technique with polarization-entangled states is presented. Polarization-entangled photons with a broad spectral width covering the telecom band are produced using a chirped periodically poled nonlinear crystal. The first demonstration of a quantum metrology application using an industrial commercial device shows a promising future for practical high-resolution quantum interference.

SOP and PMD monitoring on deployed aerial optical fibres

State of polarization (SOP) and polarization mode dispersion (PMD) are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. With 184 PMD values obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47ps and standard deviation of 0.08ps. This small standard deviation was justification for its accuracy in measuring PMD of aerial optical fibres. A comparison is also made on the accuracy of the GINTY and the FTB-5700 on measurement of PMD of aerial optical fibres with results showing that the latter is more accurate compared to the former. The time scale over which to compensate PMD in aerial optical fibres was determined and it is slightly higher than 400s; the decorrelation time obtained for SOPs on a particular windy and hot day. This is because the changes of the PMD vector are known to be slower than SOP changes.

Precise evaluation of polarization mode dispersion by separation of even- and odd-order effects in quantum interferometry

The use of quantum correlations between photons to separate measure even- and odd-order components of polarization mode dispersion (PMD) and chromatic dispersion in discrete optical elements is investigated. Two types of apparatus are discussed which use coincidence counting of entangled photon pairs to allow sub-femtosecond resolution for measurement of both PMD and chromatic dispersion. Group delays can be measured with a resolution of order 0.1 fs, whereas attosecond resolution can be achieved for phase delays.

CD-insensitive PMD monitoring based on RF power measurement

We propose and experimentally demonstrate a chromatic dispersion (CD)-insensitive first-order polarization mode dispersion (PMD) monitoring method based on radio-frequency (RF) power measurement. In high-speed (>10-GSym/s) transmission systems, a narrowband fiber Bragg grating (FBG) notch filter filters out the optical components at 10GHz away from the carrier. After square-law detection, the 10-GHz RF tone changes with PMD and is insensitive to CD, which can be used as a PMD monitoring signal. Compared with the monitoring techniques utilizing clock tone, the PMD measurement range is increased from 26.3-ps to 50-ps while the requirement of the bandwidth of photodetector is reduced from 19GHz to 10GHz in 19-Gsym/s systems. It is experimentally shown that this technique is efficient on CD-insensitive first-order PMD monitoring for 38-Gbit/s DQPSK and 57-Gbit/s D8PSK systems.

PMD Design for High-Speed WDM Backbone Network Systems Based on Field PMD Measurements

We propose a polarization mode dispersion (PMD) design for high-speed wavelength-division multiplexing (WDM) backbone network systems based on field PMD measurements on installed optical fibers for long-term commercial use. Implementing a high-speed network system on an installed fiber requires measuring PMD, because the PMD characteristics of most installed fibers are unknown. For enhanced practicality, we must be able to precisely evaluate PMD characteristics precisely with just one measurement. To understand the statistical properties of measured PMD values, we use the Jones Matrix Eigenanalysis (JME) method to conduct long-term (12 months) PMD measurements on installed fibers. We statistically analyze the measurement results and confirm that the measured values match the theory that considers the accuracy of the measurement instrument. This enables a PMD design of desired outage probability based on PMD measurements of installed fibers. We also carry out a 43-Gb/s return-to-zero differential quadrature phase shift keying (RZ-DQPSK) signal transmission with high PMD fibers in order to confirm the effectiveness of our PMD design. The PMD values of the in-line amplifier transmission line are settled so as to meet the worst value of the design. We confirm that 43-Gb/s RZ-DQPSK signals are stably transmitted at the design value.

Standard apparatus for measuring polarization mode dispersion in fiber-optic data transmission systems

Methods and instruments for ensuring the uniformity of polarization mode dispersion measurements in fiber-optic data transmission systems are described. The results of the development of a standard measuring instrument and working standards of the unit of dispersion are presented. The results of metrological investigations of a standard measuring instrument are also given.

PMD measurements based on low-coherence interferometry using a Michelson interferometer

A low-coherence technique in a Michelson interferometer for measuring polarization mode dispersion (PMD) was tested. The measured PMD mean value for one reel, in a period of several days, was 0.0405 ± 0.0008 ps/km1/2 and for the other reel, it was 0.0463 ± 0.0004 ps/km1/2. Stochastic and random PMD behavior was observed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2310–2312, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25428

High-speed polarization mode dispersion measurement using digital polarization-state generators and Mueller matrix method

A polarization-mode dispersion (PMD) measurement system using a pair of polarization-state generators (PSGs) is demonstrated. Based on the saturation characteristics of magneto-optic rotators, the PSG can be digitally controlled, ensuring high-speed and highly repeatable generation of five distinct polarization states. Thus, the PSG can make full use of the advantage of the Mueller matrix method of PMD measurement. The experimental result shows that the system has good measurement repeatability and potential for field testing.

Polarization mode dispersion spectrum measurement via high-speed wavelength-parallel polarimetry

We report experiments in which wavelength-parallel spectral polarimetry technology is used for measurement of the frequency-dependent polarization mode dispersion (PMD) vector. Experiments have been performed using either a grating spectral disperser, configured to provide 13.6 GHz spectral resolution over a 14 nm optical bandwidth, or a virtually imaged phased array spectral disperser, configured for 1.6 GHz spectral resolution over a 200 GHz band. Our results indicate that the spectral polarimetry data obtained via this approach are of sufficient quality to permit accurate extraction of the PMD spectrum. The wavelength-parallel spectral polarimetry approach allows data acquisition within a few milliseconds.

Novel Design of a Micro Gyroscope Based Birefringence Measurement for Sensor Applications

. We propose a new concept of a micro gyroscope which is made by a nonlinear micro ring resonator (i.e. 5-10 microns). The nonlinear behavior of polarized light known as polarization mode dispersion in the micro ring device is introduced by material birefringence (i.e. refractive index), which is described. In practice the measurement of polarization mode dispersion can be performed by projecting the output light into a polarizing beam splitter and detectors, where the change in phase is occurred, and then the birefringence is calculated. In addition, the property of the two orthogonal components (i.e. horizontal (H) and vertical (V) components) can be formed the photon entanglement. Which means the entangled photon can be generated, where the state timing walk-off can also be measured and compensated. The design of micro gyroscope is now capable to reduce the device scale in the micron regime to meet more possible applications such as for the measurement of temperature, pressure, and force based on birefringence sensor, which will be discussed in details.

Measuring polarization mode dispersion (PMD) in optical fibers using the nonlinear effect of four-wave mixing (FWM)

Measuring polarization mode dispersion (PMD) in optical fibers using the nonlinear effect of four-wave mixing (FWM)

Polarization mode dispersion measurement based on continuous polarization modulation

A novel technique is proposed for measurement of the group delay (GD) and the differential group delay (DGD) of optical material, components, and fiber. This new method is based on continuous polarization modulation of the stimulus optical field as opposed to sequential polarization state switching used in the traditional phase shift method. A new complete derivation of the phase shift method, based on the modified Jones calculus of elementary matrices, is presented. The derivation reveals that the phase shift measurement actually depends on all eight elementary parameters that represent DGD and optical frequency derivatives of polarization-dependent loss (PDL). Thus, the new expression for the phase shift includes the combined effect of PDL and DGD. The proposed method is evaluated by measuring a section of polarization-maintaining fiber and a 50 km length of single-mode fiber over a wavelength range from 1530 to 1610 nm. Measurements of DGD in a long single-mode fiber are shown to be highly insensitive to environmentally induced GD drift.

Evolution of PMD with the temperature on installed fiber

Polarization mode dispersion (PMD) is a stochastic, random process because each short discrete length of fiber will have a slightly different core asymmetry, and the extent of the signal degradation caused by PMD is dependent on the state of polarization of light at a given point in the fiber link, and the state of polarization of an optical signal will wander randomly because of temperature changes and mechanical stress. PMD measurements are presented in this work. Data were collected on aerial and buried optical fiber cables mixing paths. DGD data evolution for long term measurements were obtained as prior tasks for fiber characterization where 10–40 Gbit transport system based on DWDM technology will be deployed and PMD effects become significant. DGD long term measurements data have been collected using an EXFO PMD FTB-5500B Analyzer and temperature and wind speed data by the National Institute of Meteorology. Aerial fiber cable sections will be basically affected by both external agents whose effects must be also prevented before the deployment of DWDM systems that telecommunications operators use at before mentioned transmission rates. In this letter, PMD measurements were obtained from two paths or twin rings, exactly with the same length but over different fibers for each direction resulting on extracted different DGD values. The first path will be represented as clockwise direction and another one as counter-clockwise. The analysis will show that the measurements that have been presented at this job agree with those for other accepted references. It will be demonstrated how the time scale of PMD fluctuation here is strongly linked to the rate of temperature change and how the wind speed could modify the final results. Detailed graphs have been analyzed. Also theoretical and real standard deviations have been compared in order to get some conclusions about accuracy in the measurements. This review highlights a lot of trends observed on installed fibers all around the world that are similar to what the authors report here.

Statistics of the polarization mode dispersion dynamics

We characterize the joint two-time statistics of the polarization-mode dispersion (PMD) vector. Good agreement with experimental PMD measurements taken on an installed system is achieved. The results can be used to obtain the temporal evolution of the average penalty of a system close to an outage condition.