Service plane has been proposed to meet the increasing complexity in the NGON. In this paper, an in-depth research on self-adaptation service plane extension in NGON is made. Firstly, through the analysis of network developing trend and future service characteristics, the principle of introducing service plane is cleared. Then the self-adaptation technology is explained for the purpose of adapting to the development of optical network. Subsequently through the description of service self-adaptation capacity, the self-adaptation framework of service-oriented NGON is built. After that, according to the extraction of service plane functional requirements, service plane functional elements are built and the flow of access services is illustrated. Through this paper, a reference is provided for more deeply research of service optical network.
Based on the proposed polarization mode dispersion (PMD) compensation simulation model and statistical analysis method (Monte-Carlo), the critical parameters initialization of two typical optical domain PMD compensators, which include optical PMD method with fixed compensation differential group delay (DGD) and that with variable compensation DGD, are detailedly investigated by numerical method. In the simulation, the line PMD values are chosen as 3ps, 4ps and 5ps and run samples are set to 1000 in order to achieve statistical evaluation for PMD compensated systems, respectively. The simulation results show that for the PMD value pre-known systems, the value of the fixed DGD compensator should be set to 1.5~1.6 times of line PMD value in order to reach the optimum performance, but for the second kind of PMD compensator, the DGD range of lower limit should be 1.5~1.6 times of line PMD provided that of upper limit is set to 3 times of line PMD, if no effective ways are chosen to resolve the problem of local minimum in optimum process. Another conclusion can be drawn from the simulation is that, although the second PMD compensator holds higher PMD compensation performance, it will spend more feedback loops to look up the optimum DGD value in the real PMD compensation realization, and this will bring more requirements on adjustable DGD device, not only wider adjustable range, but rapid adjusting speed for real time PMD equalization.
In this paper, based on the proposed simulation model, the impact of dispersion on the systems performance in 160Gbit/s optical communication systems is detailedly discussed. As chromatic dispersion (CD) and polarization mode dispersion (PMD) are caused by different physical effect, the effects of CD and PMD on systems performance are also analyzed separately in the paper. At first, the CD and CD slope tolerance in 160Gbit/s systems are carefully simulated and analyzed, at the same time, self-phase modulation (SPM) effect is also discussed in this part, and the result shows that for 1dB eye-opening penalty, CD tolerance would be about ±3.1ps/nm and CD slope and SPM also all seriously limit the transmission distance of systems. Furthermore, the impact of PMD on systems property are discussed by virtue of statistical method, and result shows that PMD tolerance of 160Gbit/s is 0.7ps with the outage probability of 10-5 of 1dB eye-opening penalty and it will increase to 1.8ps for the first-order PMD compensated systems. These results show that CD, CD slope, PMD and SPM all are key challenges in 160Gbit/s systems.
We demonstrate the combined effects of SPM, GVD, and PMD-induced eye-diagram penalties by means of numerical simulations for 40Gbit/s NRZ and RZ modulation formats. Considering all orders of PMD, we choose a fixed state of input polarization (SOIP) and do the simulation 1000 times for each input average power, and then get the Q-penalty of eye-diagram by exponential extrapolation method for cumulative probability 10-5. When input average power is less than 0dBm, SPM effect is very weak and GVD is compensated completely, only PMD takes effect in this power area. The Q-penalties are constants for NRZ and RZ with different PMD values. As input average power increasing, SPM takes effect gradually. First order PMID can suspend the SPM affection, and the higher PMD value, the more postponement is observed. The Q-penalty contributed by higher order PMID has close relation with spectrum width of signal. For NRZ signal with chirp=-0.7, the interactions between SPM and chirp can decrease spectrum width of signal; the Q-penalty contributed by higher order PMD will decrease correspondingly. For RZ with duty 0.3, the changing of the root mean square (RMS) spectrum width induced by the interactions of SPM and chirp is not obviously in this case, the Q-penalties of SPM+GVD+PMD increase consistently. When SPM effect is too strong (For example: for NRZ, average power larger than 10dBm; for RZ with duty 0.3, average power larger than 6dBm.), the interactions of SPM+GVD+PMD will cause the seriously degradation of system performance for any duty cycle and PMID value. Under our simulation conditions, the narrower pulse-width, the less Q-penalty until duty cycle decreases to 0. 1.
Based on the modeling of considering polarization mode dispersion (PMD) and polarization-dependent loss (PDL) simultaneously, the impact ofPDL on high-speed PMD compensation systems is discussed in this paper. The simulation result shows that for the 4OGbit/s NRZ systems being PMD value 8ps, if the PDL value of single device increases to 0.7dB, the infkience of PDL on the systems performance is obvious. Furthermore, if it reaches to 1.5dB, the outage probability of eye-opening penalty of PMD compensation system will increase from 10-6 (in case no PDL effect) to 10-4.Therefore, it is necessary to considering the impact of PDL on systems performance in the PMD compensation systems design ifthe PDL value ofdevice reaches to 0.7dB or beyond
As bit-rate in optical fiber communications system increases to 4OGbit/s or beyond in single channel, polarization mode dispersion (PMD), especially higher-order PMD, has become one of major obstacles in high-speed and long-distance transmission systems. Therefore, it is obvious that there are two ways to think of higher-order PMD, one is to investigate that how the higher-orderPMD affect system performance and its critical limitation value; the other is to find effective methods to mitigate or compensate higher-order PMD to improve system performance. Therefore, in this paper, firstly a detailed discussion will focus on the system impairment due to higher-order PMD, secondly, a improved first-order PMD compensation method is proposed to compensate part of higher-order PMD and checked with numerical simulation.
Based on the segmented bi-refringent fiber model, the penalties due to PMD, GVD and nonlinearity effects in 4x400bit/s WDM systems is calculated by solving the coupled nonlinear Schrodinger equation in bi-refringent fiber with split-step Fourier method for different PMD values in this paper. The simulation results show that in a WDM system the outage probability for one channel is not much larger than that in other channels. For PMD compensation in WDM system it runs a dangerous risk to only compensate the worst channel at a time, and it might be necessary to compensate all channels simultaneously.
An effective way to evaluate the performance of PMD compensation, which uses a proposed polarization-mode dispersion (PMD) emulator, has been studied recently. In this paper, we first present a theoretical analysis on a special model of PMD-emulator (PMDE), then explain the first and second-order PMD effects, which are very useful to value the impact of high-order PMD on pulse. Numerical and experimental results show that PMDE can emulate the statistics property and cover the range of high-order parameter of the real fiber successfully. The impact of second-order PMD on pulse for 40Gbit/s optical fiber communication is also presented as the simulation results.
In this paper, the characteristics of higher-order PMD up to third order and its impact on transmission systems are mainly studied. Based on the concept of second order principal states of polarization (PSPs) put forward in the paper, the covered ranges of higher-order PMD parameters with the increasing instantaneous differential group delay (DGD) value are investigated by simulation. It shows that the upper covered range of PSP rotation rate decreases rapidly with increasing instantaneous DGD until the DGD reaches the PMD value of the fiber, and then continues to slowly decrease. This may cause serious signal distortion due to fast PSP rotation rate even DGD at the low value. Furthermore, to that of the second order PSP rotation rate and that of second order PMD vector magnitude, they increase simultaneously with increasing instantaneous DGD until the DGD reaches about 2 times PMD value of the fiber, then turn to decrease. This may has an impact on the performance of higher-order PMD compensators. At the same time, the simulation results show that higher-order PMD parameters can impose serious signal distortion on 40 Gbit/s systems and the higher PMD value, the higher higher-order PMD influence on signal distortion.
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