456 research outputs found
Nonlinear propagation equations in fibers with multiple modes—Transitions between representation bases
No full textThe 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
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
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 textOn the Secrecy Capacity of the Space-Division Multiplexed Fiber Optical Communication Systems
No full textGuest Editorial OFC 2017 Special Issue
No full textThe papers included in this special issue were presented at the Optical Fiber Communications Conference (OFC) 2017, which took place in March in Los Angeles, CA
Gridless optical networking field trial: flexible spectrum switching, defragmentation and transport of 10G/40G/100G/555G over 620-km field fiber
No full textWe report the first gridless networking field trial with flexible spectrum switching nodes over 620 km field fibre links. Successful transport, spectrum switching and defragmentation achieved for mixed line signals including 555G and coherent 100G
de Haas-van Alphen effect and the Fermi surface of PrNi
No full textThe Fermi surface of PrNi5 has been studied by the
measurements of the de Haas-van Alphen (dHvA) effect at
temperatures between 0.3 and 1.8{ K} in magnetic
fields up to 12 T. Two dHvA frequencies have been obtained.
The electronic structure of PrNi5 was calculated
using the full potential linearized augmented plane wave method. Five
sheets of the Fermi surface and the multiple
extremal cross sections were determined. First and second
sheet have a hole-like structure. The agreement
between theory and experiment is obtained by a small
downward shift (≈ 0.1 eV) of the Fermi energy which is probably
due to an underestimation of the
role of 4f electrons
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