The paper discusses uncertainty in estimation of sign of accumulated chromatic dispersion in an optical fiber communication link where the estimation is based on fitting a model of chromatic dispersion affected optical intensity waveforms to intensity measurement data. The uncertainty is characterized by probability of false readout of accumulated chromatic dispersion sign. Through extensive computations it is shown that despite the sign estimation in the method in question is in general ambiguous the chance for erroneous readout can be engineered to a desired level provided certain conditions are met. For the purpose of the characterization a theoretical model of sign false readout was developed and validated through combined measurements and simulations.
A possibility is shown of a non-disruptive estimation of chromatic dispersion in a fiber of an intensity modulation communication line under work conditions. Uncertainty of the chromatic dispersion estimates is analyzed and quantified with the use of confidence intervals.
A possibility to estimate parameters of the first order model of PMD in a fiber of an intensity modulation communication line with non-zero residual chromatic dispersion is shown. Uncertainty of the PMD estimates is analyzed and quantified with the use of confidence intervals.
The paper discusses uncertainty of estimates of the first order PMD parameters in a fiber in the context of their use to characterize quality of optical fiber communication lines. It was recently shown that when the parameters are estimated from waveforms of the signal transmitted through a fiber the uncertainty of the estimates can be considerably large. The results however, were based on an approximation which might not reproduce well the distribution of the parameters, particularly in the tail. This may lead to overestimation of uncertainty, the most influential in the range of low DGD values. The paper presents the method in which a more exact approximation can be obtained and provides estimate uncertainty results for this specific range.
The paper proposes a method to quantify inaccuracy of the DGD estimation in which the propagation model neglects nonlinearities in an optical fiber and presents the results of the assessment. The practical limits for the application of the linear model can be learnt. The outcome of the paper can be used as a source for design directions for in-work DGD monitoring systems for optical communications.
The paper concerns uncertainty of PMD Eye Opening Penalty (EOP) in an OOK fiber optic communication line that
may result from the use in EOP calculations of uncertain estimates of the first order PMD. The considered PMD
estimator obtains the PMD values from waveforms of transmitted signals. It is shown that non-negligible uncertainty and
bias that the PMD estimates suffer from do not translate to unacceptable uncertainty of EOP calculated from the
estimates. Then, practical applicability of PMD estimation from waveforms can be confirmed.
A possibility to estimate parameters of the first order model of PMD in a fiber of a communication line is shown. The suggested estimator is based on the maximum likelihood principle. The appropriate measures for quality of the estimator are proposed and used for its characterization.
A possibility to estimate chromatic dispersion from telecom signals in an OOK optical communication link with non-zero chirp modulator without resorting to phase measurements is presented. The model relating intensities at the transmitter and receiver sides is built for a link affected by chromatic dispersion and estimation procedure is proposed. Validity of the method is shown in a laboratory experiment.
KEYWORDS: Switches, Switching, Solar energy, Electro optics, Control systems, Signal attenuation, Power supplies, Passive optical networks, Photovoltaics, Optical switching
Paper presents three optically supplied protection systems developed for use for a fiber segment in a Passive Optical Network and gives assessment and comparison of their characteristics with respect to application of an optical supply.
The article describes methodology and results of research on remote optical power supply at low illumination levels.
Such approach is a result of studies on passive optical networks extended with optically powered active components
made beforehand.
On the foundation of joint experience acquired by several research centres there was defined the roadmap to the desired single technological platform for fabrication of a specific class of photonic integrated circuits, which are controlled by mechanical means. In the paper the challenges of fabrication of such photonic circuits are discussed. The main arguments in favour of the Silicon-on-Insulator materials system as the basis for the platform are presented. Options for the mechanics-to-optics arrangement, materials and processes are described and illustrated with the current achievements from the authors' labs. In the roadmap the preference is given to the vertical arrangement in which, the mechanical part is stacked above the waveguiding layer. A flexible trimming routine is designed to complement the process flow if the technologies developed cannot provide the required reproducibility.
Most approaches to perform switching and tuning in photonic integrated circuits (PICs) are based on modulation of effective refractive index of a waveguide or a resonant structure and use a variety of means by which the desired perturbation of index is to be achieved. Limitations to these methods, which obstacle achievement of the desired results, are discussed. It is shown that the promising alternative, at least for applications, for which speed is not a critical issue, can be to control light by means of nano/micromechanic actuation. The general idea is presented and the applicability of mechanical actuation to very-large-scale integration (VLSI) photonics is assessed. Particular concepts of switching and tuning are described.
The paper presents an idea of a reconfigurable optical add-drop multiplexer (ROADM) based on micro/nanomechanically switched micro-ring resonators. Main issues related to the design and fabrication of mechanically controlled ROADM are discussed.
Properties of SS-WDMA and FE-CDMA data communication networks were considered. Networks of both types were compared with respect to attainable throughput and size as well as data channel characteristics. Practical limitations to applications of SS-WDMA and FE-CDMA are discussed.
Self referenced and absorption modulation methods for detecting gas pollutants were described. Applicability of both methods was tested experimentally.
The paper discusses technical feasibility of using fiber optics technology for underground mine communication systems. The emphasis has been placed on sensor dedicated systems for methane monitoring, fire detection, and vibration sensing. Communication system included video, voice and data transmission has been proposed. The test procedure and requirements for the fiber optics network in the adverse coal mining are given. The network has been developed and evaluated in a number of underground mine applications. The long term environmental trials and laboratory examinations have resulted in approval fiber optic network for in-mine use.
Some problems of applications of the fiber optic networks for mining seismology are presented. A structure of the network multiplexing and modulation techniques transmission quality and design aspects are discussed with respect to mining environmental conditions typical topologies and mining technical standards. Emphasis is laid on compliance with requirements of safe operation in mining environment. An example network is presented. The network has been given official approval for inmine practice. It serves for monitoring crump hazard in one of coal mines in Poland.
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