1,720,974 research outputs found
Quantum Limits on the Energy Consumption of Optical Transmission Systems
No full textThe search for schemes that minimize the energy associated with the transmission of information is a longstanding fundamental issue in communication theory. In this paper we extend fundamental limits to the energy consumption per unit of information, as given by Shannon’s theory, to the quantum domain. Unlike previous studies, we address a scenario where the signal may be manipulated in an arbitrary way while propagating from the transmitter to the receiver. This situation characterizes many realistic scenarios, such as multi-span fiber-optic communication systems. We obtain the ultimate quantum limit on the energy consumption in this scenario and propose a simple binary energy modulation scheme that approaches this limit within one order of magnitude for practically relevant values of spectral efficiency. Under the same conditions, the quantum energy consumption limit of the standard optically amplified coherent communication scheme is three orders of magnitude above the ultimate identified limit. Throughout the paper we consider transmission of classical information over a quantum channel
Stokes-space analysis of modal dispersion in fibers with multiple mode transmission
No full textModal dispersion (MD) in a multimode fiber may be considered as a generalized form of polarization mode dispersion (PMD) in single mode fibers. Using this analogy, we extend the formalism developed for PMD to characterize MD in fibers with multiple spatial modes. We introduce a MD vector defined in a D-dimensional extended Stokes space whose square length is the sum of the square group delays of the generalized principal states. For strong mode coupling, the MD vector undertakes a D-dimensional isotropic random walk, so that the distribution of its length is a chi distribution with D degrees of freedom. We also characterize the largest differential group delay, that is the difference between the delays of the fastest and the slowest principal states, and show that it too is very well approximated by a chi distribution, although in general with a smaller number of degrees of freedom. Finally, we study the spectral properties of MD in terms of the frequency autocorrelation functions of the MD vector, of the square modulus of the MD vector, and of the largest differential group delay. The analytical results are supported by extensive numerical simulations
Nonlinear propagation equations in fibers with multiple modes—Transitions between representation bases
Get PDFThe transverse pattern of the field that propagates in a fiber supporting multiple modes can always be described as a superposition of the patterns of the individual fiber modes. Yet, the use of other bases is often found to be more convenient, with the most famous example being that of linearly polarized modes in weakly guiding fibers. The nonlinear propagation equations contain coefficients that involve overlap integrals between the lateral profiles of multiple propagation modes. A fundamental question that has been raised in this context is whether it is legitimate to compute these coefficients from the overlap integrals between elements of alternative bases for the field representation. In this paper, we show that the answer to this question is positive in the most general sense. This result is significant in the context of space-division multiplexed transmission in multi-mode and multi-core fibers
Physical layer security of space-division multiplexed fiber-optic communication systems in the presence of multiple eavesdroppers
No full textAn error probability approach for quantifying physical layer security of MIMO-SDM systems
No full textPhysical layer security in space-division multiplexed fiber optic communications
No full textRecent developments in the field of space-division multiplexing (SDM) for fiber-optic communication systems suggest that the spatial diversity offered by SDMcan be used not only to increase system capacity, but also to achieve provable security against physical layer attacks. In this work, we outline some of the mathematical framework necessary to assess the security benefits of the SDM. We substantiate our conjecture that allocating the maximal allowable power to each mode is optimal in terms of physical layer security. Further more, we expand the scope of our security analyses to include distortion as a quantitative metric for secrecy and study how the rate of reliable communication between the legitimate transmitter-receiver pair can be chosen to maximize reconstruction (decoding) errors of the eavesdropper. © 2012 IEEE
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Adaptive MIMO signal processing for mode-division multiplexing
No full textThe fiber-optic multiple-input multiple-output (MIMO) channel is analyzed. For a 6×6 MIMO experiment over 96 km few-mode fiber it is found that the mode dependent loss is 3 dB, with negligible temporal fluctuations and almost no impact on capacity. © 2012 OSA
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