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Optical multi-band (OMB) systems exploit the low-loss spectrum of the single mode fiber (SMF) and are key enablers to increase the transportation capacity and node connectivity of already deployed systems. The realization of OMB systems is mainly based on the technological advances on the component and system level, and for this purpose, a broad gamut of various structural elements, such as transceivers, amplifiers, filters, etc. have been commercialized already or are close to commercialization. This wide range of options, which aid in unlocking the concurrent transmission in all amplification bands, is reviewed here for the first time, whilst their pros and cons as well as their limitations are discussed. Furthermore, the needs for additional components in order to fully exploit the -390 nm low-loss wavelength range of SMF, which spans from 1260 to 1650 nm, are highlighted. Finally, based on a physical layer formalism, which incorporates the impact of the most important physical layer constraints for an OMB system, the attainable capacity and transparent reach of each amplification band are quantified. [ABSTRACT FROM AUTHOR]

This paper investigates for rising optical fiber transmission strength, increasing bandwidth, and decreasing communication system weakness by using wavelength division multiplexing (WDM). WDM gives today's distention speed and communication traffic. Systems using WDM faces nonlinearities, which the most intensive nonlinear attack is, four wave mixing (FWM). FWM creates and increases crosstalk between WDM channels as a result slows down and impairs the performance of the communication system. This investigation uses orthogonal frequency division multiplexing (OFDM) for evaluating execution of WDM fiber system by repairing Polarization Mode Dispersion (PMD). We took results in the case of trying PMD-Emulator and without trying PMD-Emulator in the system design. We compared the results got in both cases. Furthermore, we compared the performance of the system with the investigations done using different ways, methods, and techniques for compensating PMD and FWM appears in WDM systems. As PMD-Emulator, helps enhancing the system design performance, and OFDM gives the feature of robustness and useful execution to the system. OFDM examined by appointing interfered orthogonal signal sets, for 16 channels; with equally spaced OFDM channels. Oure results showed that the optical fiber communication system using OFDM technique gives perfect removing FWM signal crosstalk, and accurate data transmission, comparing to other techniques used in other researches. We got a decreased FWM power to -77dBm, and the BER of -0.317. Furthermore, the system quality increased with applying PMD-Emulator and OFDM. In addition, using PMD-Emulator in the system design raised the results effectiveness. The program used in the present work is optisystem-15, and the results obtained in this study coincide with the theoretical and actual results obtained by the previous studies. [ABSTRACT FROM AUTHOR]

In order to separate the multiplexed beams with different wavelengths in an all-fiber network, a novel concept of distinguishing different wavelengths by the orbital angular momentum (OAM) beams [i.e., L(topological charge) =1 and $L=-1$ ] based on the OAM fiber is proposed and investigated in the theory and experiments. Meanwhile, a new OAM fiber supporting the first order vector modes (i.e., TE0,1, HE2,1, and TM0,1) is also designed and fabricated. For the sake of verifying the feasibility of the proposed scheme, an experimental platform is anticipated and established. Bit error rates (BERs) and constellation diagrams are employed to evaluate the performance of the proposed schemes with respect to the transmission rate of data (V) and the difference of wavelength between the two input lasers. The simulated and measured results demonstrate that two different wavelengths (i.e., 1548 and 1545 nm) with the cycle of 14 and 10 nm can be distinguished though two OAM beams (i.e., $L=1$ and $L=-1$), respectively. The measured BERs and constellation diagrams with respect to data rates (V) depict that the performance of the proposed schemes degenerates with the increment of data rates (V) from 5 to 40 Gb/s. Similarly, the measured BERs and constellation diagrams with respect to the difference of wavelengths also demonstrate that the performance of the proposed scheme can be improved by increasing the difference of wavelengths from 1 to 4 nm. [ABSTRACT FROM AUTHOR]

The phenomenon of modal noise, which is typically undesired within fiber optic links, is exploited advantageously to characterize vertical cavity surface emitting lasers (VCSELs) operating in the first optical window (wavelength $\lambda \simeq 850$ nm), in terms of frequency chirping. The proposed method, which can be applied utilizing ordinary laboratory components and instrumentation, contributes to fill an existing gap. Indeed, the methods which are typically exploited to determine this undesired optical frequency modulation can be straightforwardly applied only to sources operating at wavelengths of 1310 and 1550 nm, while they become unpractical or even inapplicable at wavelengths of 850 nm. Through the proposed technique, the evaluation of chirp coefficient $M$ and phase difference $\psi $ between frequency and intensity modulation (or equivalently linewidth enhancement factor $\alpha $ and chirp scaling factor $\kappa $) of VCSELs can be performed. This allows the correct design of various types of fiber optic links, making possible to take advantage of these low-cost and low-consumption optical sources. [ABSTRACT FROM AUTHOR]

We report a large mode area (LMA), Ge11.5As24Se64.5 six-fold symmetry quasi-periodic dual cladding leakage channel fiber (LCF) for supercontinuum generation (SCG) from 2 to 15~\mu \textm wavelengths. The proposed LMA fiber exhibits single-mode behavior by means of higher order mode delocalization for the entire wavelengths. Besides, the LCF possesses two zero dispersion wavelengths at 4.36 and 14.16~\mu \textm . Indeed, we numerically demonstrated the spectral broadening of continuum for the first time from 2 to 15~\mu \textm in the quasi-periodic dual cladding LCF for a length of 10 mm. It is observed that the red-shifted soliton at the centre wavelength of 9.42~\mu \textm obtain an energy of 0.164 nJ for a low input energy of 0.2 nJ. Further, the SCG in the proposed LCF attains a high conversion efficiency of 82 % at the solitonic spectrum and broadest spanning from 2 to 15~\mu \textm for the low input energy of 0.2 nJ. Thus, the proposed LCF-based SC source is the best choice for the applications, such as optical sensing, optical communication, food quality monitoring, and early cancer diagnostics. [ABSTRACT FROM PUBLISHER]

A mathematical framework is presented to study the evolution of multi-point cumulants in nonlinear dispersive partial differential equations with random input data, based on the theory of weak wave turbulence (WWT). This framework is used to explain how energy is distributed among Fourier modes in the nonlinear Schrödinger equation. This is achieved by considering interactions among four Fourier modes and studying the role of the resonant, non-resonant, and trivial quartets in the dynamics. As an application, a power spectral density is suggested for calculating the interference power in dense wavelength-division multiplexed optical systems, based on the kinetic equation of the WWT. This power spectrum, termed the Kolmogorov-Zakharov (KZ) model, results in a better estimate of the signal spectrum in optical fiber, compared with the so-called Gaussian noise model. The KZ model is generalized to non-stationary inputs and multi-span optical systems. [ABSTRACT FROM PUBLISHER]

To increase the transmission capacity of optical fiber transmission systems, we have developed a multiplexer- digital-to-analogue converter and an optical time-division multiplexing modulator, which respectively generate high-speed signals in the electronic and optical domains. With these devices, we can significantly increase the capacity per wavelength channel. [ABSTRACT FROM AUTHOR]

This paper presents a teletraffic study that evaluates the benefits of a passive optical access network, fix/mobile, by multiplexing wavelength division (WDM-PON) in which it is appreciated the impact of including extra wavelengths channels for the transmission of multicast services versus the multicast transport service using replicated unicast connections. The conclusion is that under heavy bulk-data traffic, the nominal data rate and tolerated efficiency are defined by the maximum number of out-of-profile users permitted for every multicast solution. Specifically, for the high values of efficiency the channels of extra wavelength avoid the need of multicast wavelengths used only when there is a fraction (significantly small) of out-of-profile users (5%). [ABSTRACT FROM AUTHOR]

In this article, we present the concept of the filterless optical network from a control plane perspective, defining the network and showing to what extent a control plane could be adapted to it. Then we propose a control plane architecture and study its performance. Filterless networks act as passive broadcast and select networks, in which active switching elements, such as the wavelength selection switch, are replaced by passive optical splitters and combiners, and network agility is provided by tunable transceivers. We introduce the concept of unfiltered channels and that of backward and forward ports, and show how they impact topological performance, and, in particular, the fact that wavelength usage increases greatly as the protection ratio shrinks. [ABSTRACT FROM PUBLISHER]

This paper presents a new passive optical network (PON) architecture that applies an optical multicast capable switch (OMS) to direct wavelengths to a set of PON branches and enables them to share the transceivers in the central office (CO) on demand. The OMS is composed of fiber splitters and switching gates, and by controlling the on-off gates the wavelengths at the inputs can reach any outputs of the OMS. Through the OMS configuration, logical PONs are dynamically formed according to changing traffic patterns, and traffic is further scheduled in the time domain within each logical PON. The proposed network achieves network resource sharing without requiring tunable transceivers or wavelength filters, and without changing deployed network devices in the field or at the user end. Analysis and experimental study results show the efficiency of resource sharing and demonstrate the concept of resource sharing among PON branches. [ABSTRACT FROM AUTHOR]

A micro-displacement sensor consisting of a fiber-loop made with a tapered fiber is reported. The sensor operation is based on the interaction between the fundamental cladding mode propagating through the taper waist and higher order cladding modes excited when the taper is deformed to form a loop. As a result, a transmission spectrum with several notches is observed, where the notch wavelength resonances shift as a function of the loop diameter. The loop diameter is varied by the spatial displacement of one end of the fiber-loop attached to a linear translation stage. In a displacement range of 3.125 mm the maximum wavelength shift is 360.93 nm, with 0.116 nm/μm sensitivity. By using a 1,280 nm broadband low-power LED source and a single Ge-photodetector in a power transmission sensor setup, a sensitivity in the order of 2.7 nW/μm is obtained in ∼1 mm range. The proposed sensor is easy to implement and has a plenty of room to improve its performance. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of a gigahertz clock rate environmentally robust phase-encoded quantum key distribution (QKD) system utilizing several different single-photon detectors, including the first implementation of an experimental resonant cavity thin-junction silicon single-photon avalanche diode. The system operates at a wavelength of 850 nm using standard telecommunications optical fibre. A general-purpose theoretical model for the performance of QKD systems is presented with reference to these experimental results before predictions are made about realistic detector developments in this system. We discuss, with reference to the theoretical model, how detector operating parameters can be further optimized to maximize key exchange rates. [ABSTRACT FROM AUTHOR]

Optimization of the AIAsSb-InGaAs-AIAs coupled double-quantum-wells in optical waveguide core for optimal pump-induced refractive-index change indicates that thin AlAs center barrier leads to larger refractive-index change, and the InGaAs double-quantum-wells have an optimum thickness of which maximum refractive-index change is obtained. Analysis shows that the cross phase-modulation efficiency of these optical waveguides is highly dependent on optical confinement and is limited to approximately 0.05 rad/pJ in the 1550 nm region as far as the cross phase-modulation based on free-carrier mass dispersion effect is concerned. [ABSTRACT FROM AUTHOR]

Recently, metropolitan and access communication networks have markedly developed by utilizing a variety of technologies. Their bearer communication infrastructures will be mostly exploiting the optical transmission medium where wavelength division multiplexing techniques will play an important role. This contribution discusses the symmetric sharing of common optical network resources in wavelength and time domains. Wavelength-Division Multiplexed Passive Optical Networks (WDM-PON) attract considerable attention regarding the next generation of optical metropolitan and access networks. The main purpose of this contribution is presented by the analysis of possible scheduling of wavelengths for our novel hybrid network topologies considered for WDM-PON networks. This contribution briefly deploys adequate Dynamic Wavelength Allocation (DWA) algorithms for selected WDM-PON network designs with the provision of traffic protection when only passive optical components in remote nodes are utilized. The main part of this study is focused on the use of wavelength scheduling methods for selected WDM-PON network designs. For evaluation of offline and online wavelength scheduling for novel hybrid network topologies, a simulation model realized in the Matlab programming environment allows to analyze interactions between various metropolitan and access parts in the Optical Distribution Network (ODN) related to advanced WDM-PON network designs. Finally, wavelength scheduling methods are compared from a viewpoint of utilization in advanced WDM-PON networks designs. [ABSTRACT FROM AUTHOR]

Operating principle for a flip-flop memory cell based on erbium-doped devices is presented. A complete model for memory dynamics is introduced taking into account, at the same time, for memory writing, reading, and erasing. Simple equations are found relating writing, spontaneous and stimulated erasing times to device physical parameters, signals wavelength and power. In principle, for example, increasing writing and erasing energies at the appropriate wavelength it is possible to dramatically reduce transition times. Extinction ratio (ER) is also determined as a function of host medium, and signals properties. An optimization technique is proposed for erasing signal design in order to guarantee maximum ER. Numerical example are provided for Er and Er-Yb doped fibers whose doping ion density isp = 1.1413·1024 ions/m³, and 2.0·1025 ions/m³, respectively. Finally, an experimental demonstration giving an Er higher than 5 and 16 dB for the two fibers, respectively, is provided and discussed. [ABSTRACT FROM AUTHOR]

This paper discusses merits and drawbacks of the Optical Burst Switching (OBS) paradigm, which received so much attention by the academic research community. Since the topic is hot, and given the several flavors of OBS available in the literature, we first define what we mean by OBS. Then, we carefully design a reference scenario and a set of evaluation experiments that can be used to obtain quantitative answers to interesting questions in a repeatable way. Within this framework, we motivate our skepticism towards two frequent assertions about the OBS paradigm: its ability to (i) exploit the network bandwidth more efficiently than Optical Circuit Switching (OCS) alternatives, and (ii) to efficiently solve contentions without optical buffers. [ABSTRACT FROM AUTHOR]

Building on the Ethernet Passive Optical Network (EPON) and Gigabit PON (GPON) standards, Next-Generation (NG) PONs (i) provide increased data rates, split ratios, wavelengths counts, and fiber lengths, as well as (ii) allow for all-optical integration of access and metro networks. In this paper we provide a comprehensive probabilistic analysis of the capacity (maximum mean packet throughput) and packet delay of subnetworks that can be used to form NG-PONs. Our analysis can cover a wide range of NG-PONs through taking the minimum capacity of the subnetworks forming the NG-PON and weighing the packet delays of the subnetworks. Our numerical and simulation results indicate that our analysis quite accurately characterizes the throughput-delay performance of EPON/GPON tree networks, including networks upgraded with higher data rates and wavelength counts. Our analysis also characterizes the trade-offs and bottlenecks when integrating EPON/GPON tree networks across a metro area with a ring, a Passive Star Coupler (PSC), or an Arrayed Waveguide Grating (AWG) for uniform and non-uniform traffic. To the best of our knowledge, the presented analysis is the first to consider multiple PONs interconnected via a metro network. [ABSTRACT FROM AUTHOR]