1,720,984 research outputs found
Coherent detection with an incoherent local oscillator
Full text linkWe demonstrate the feasibility of fully coherent reconstruction of the complex envelope of arbitrary optical fields while using an incoherent source as a local oscillator (LO). The reconstruction relies on a signal processing procedure that we describe, and the only requirement from the system is that the receiver’s electrical bandwidth and sampling rate are at least twice as high as the bandwidth of the received signal and of the LO. The proposed scheme is particularly attractive in spectral regions where no high-quality lasers are available
Kramers-Kronig coherent receiver
Full text linkThe interest for short-reach links of the kind needed for inter-data-center communications has fueled in recent years the search for transmission schemes that are simultaneously highly performing and cost effective. In this work we propose a direct-detection coherent receiver that combines the advantages of coherent transmission and the costeffectiveness of direct detection. The working principle of the proposed receiver is based on the famous Kramers-Kronig (KK) relations,and its implementation requires transmitting a continuous-wave signal at one edge of the information-carrying signal spectrum. The KK receiver scheme allows digital postcompensation of linear propagation impairments and,as compared to other existing solutions,is more efficient in terms of spectral occupancy and energy consumption
Modeling of nonlinear propagation in space-division multiplexed fiber-optic transmission
No full textIn recent years, space-division multiplexed (SDM) transmission in multimode and multicore fiber structures has been attracting growing interest as a mean of scaling the capacity of the optical transport network. As in the case of standard systems based on the single-mode fibers, the ultimate limit to the achievable transmission rate is set by the nonlinearity of the fiber, and hence, the accurate modeling of nonlinear propagation in SDM fibers is a critical task. A key feature of long multimode fiber structures that are relevant for communications is the existence of random coupling between modes. This coupling has a major effect on the properties of nonlinear propagation, and in its presence, the coupled nonlinear Schrödinger equations, which are characterized by a very large number of propagation constants, reduce to the much simpler form of the coupled generalized Manakov equations. These equations shed light on the relevant aspects of signal propagation dynamics, and facilitate the establishment of an intuitive physical picture. Another key feature of SDM fibers is the existence of modal dispersion that introduces frequency dependence into the mode mixing process and modifies the effects of nonlinear propagation. In this paper, we review all of the above mentioned phenomena, and in addition, we assess the way in which the information capacity of SDM fibers is expected to scale with the number of propagation modes. Finally, we extend the Manakov formalism so as to account for the noninstantaneous Raman contribution to the nonlinear response of silica
Pulse Collision Picture of Inter-Channel Nonlinear Interference in Fiber-Optic Communications
No full textWe model the build-up of inter-channel nonlinear interference noise (NLIN) that is generated by cross-phase-modulation in wavelength division multiplexed systems by considering the pulse collision dynamics in the time domain. The fundamental interactions can be classified as two-pulse, three-pulse, or four-pulse collisions, and they can be either complete, or incomplete. Each type of collision is shown to have its unique signature and the overall nature of NLIN is determined by the relative importance of the various classes of pulse collisions in a given wavelength division multiplexed (WDM) system. The pulse-collision picture provides qualitative and quantitative insight into the character of NLIN, offering a simple and intuitive explanation to all of the reported and previously unexplained phenomena. In particular, we show that the most important contributions to NLIN follow from two-pulse and four-pulse collisions. While the contribution of two-pulse collisions is in the form of phase-noise and polarization-state-rotation with strong dependence on modulation format, four-pulse collisions generate complex circular noise whose variance is independent of modulation format. In addition, two-pulse collisions are strongest when the collision is complete, whereas four-pulse collisions are strongest when the collision is incomplete. We show that two-pulse collisions dominate the formation of NLIN in short links with lumped amplification, or in links with distributed amplification extending over arbitrary length. In long links using lumped amplification, the relative significance of four-pulse collisions increases, emphasizing the circularity of the NLIN while reducing its dependence on modulation format. © 1983-2012 IEEE
Correlations and phase noise in NLIN-modelling and system implications
No full textWe present a method for the accurate prediction of BER in nonlinear systems, taking into account the temporal correlations of the nonlinear interference noise and incorporating the effect of an adaptive receiver
Modeling the Bit-Error-Rate Performance of Nonlinear Fiber-Optic Systems
No full textWe present a detailed statistical model of nonlinear interference noise (NLIN) in optical communication systems. We demonstrate an efficient method of calculating second-order statistics of the NLIN coefficients, particularly their temporal autocorrelation and cross correlation. The model is highly accurate in predicting system performance metrics such as bit-error-rate and signal-To-noise ratio, and is shown to provide better accuracy with respect to models that use the NLIN variance alone, particularly when accounting for the adaptive filtering of realistic receivers. © 1983-2012 IEEE
Nonlocal compensation of polarization mode dispersion in the transmission of polarization entangled photons
No full textWe study the feasibility of nonlocally compensating for polarization mode dispersion (PMD), when polarization entangled photons are distributed in fiber-optic channels.We quantify the effectiveness of nonlocal compensation while taking into account the possibility that entanglement is generated through the use of a pulsed optical pump signal. © 2011 Optical Society of America
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