Wdm

This paper reports the effects of pre- and post-compensation using CRZ modulation format in long-haul WDM optical transmission link using wavelengths in three bandwidths viz. 1537.4; 1550; 1562.6 nm at per channel bit rates of 10 Gbit/s. It has been investigated here that optimization of dispersion map results in improved management of nonlinear effects in long-haul light wave systems operating in the quasi-linear regime. In addition, pre- and post-dispersion compensation was applied at the transmitter and receiver depending on the signal wavelength, which resulted in improvement of performance metrics viz. Q2 (dB), BER and OSNR over longer transmission distances. It is reported here that optimum values of Q2 dB of 17.1 dB, BER of 8.4933e−015 and OSNR of 30.1 dB are obtained at 1550 nm at a transmission distance of 7360 km with pre- and post-compensation using CRZ modulation format.

Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. In this article we survey two new technologies which are still in the experimental stage -optical packet switching and optical burst switching -and comment on their suitability for transporting IP traffic.

Wideband Ti : LiNbO 3 optical modulators for 40 Gb/s applications, Proc. ECOC'98, Madrid, Spain, 1998, pp. 547-548. 24. S. Yamada and M. Minakata, DC drift Phenomenon in LiNbO 3 optical waveguide devices, Jpn. J. Appl. Phys. 20: 733-737 (1981). 25. M. Seino, T. Nakazawa, M. Doi, and S. Taniguchi, The long term reliability estimation of Ti : LiNbO 3 modulator for DC drift, Proc. IOOC'95, Hong Kong, paper PD1-8, 1995, pp. 15-16. 26. I. Sawaki, H. Nakajima, M. Seino, and K. Asama, Thermally stabilized z-cut Ti : LiNbO 3 waveguide switch, Proc.

Rapidly-increasing traffic demands will require the upgrade of optical access networks, namely deployed Passive Optical Networks (PONs), which may soon face capacity exhaustion. Such upgrade options must consider several technical and cost factors for evolution towards a shared multiple-channel PON using Wavelength-Division Multiplexing (WDM). WDM can facilitate the seamless upgrade of PONs, since capacity can be increased by adding new wavelength channels. We study the requirements for optimal migration towards higher bandwidth per user, and examine scenarios and cost-effective solutions for PON evolution.

With standard assumptions the routing and wavelength assignment problem (RWA) can be viewed as a Markov Decision Process (MDP). The problem, however, defies an exact solution because of the huge size of the state space. Only heuristic algorithms have been presented up till now. In this paper we propose an approach where, starting from a given heuristic algorithm, one obtains a better algorithm by the first policy iteration. In order to estimate the relative costs of states, we make a simulation on the fly studying, at each decision epoch, the consequences of all the alternatives actions. Being computationally intensive, this method can be used in real time only for systems with slow dynamics. Off-line it can be used to assess how close the heuristic algorithms come to the optimal policy. Numerical examples are given about the policy improvement.

Future avionics systems will require high-bandwidth on-board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fiber optic communication technology can meet all these challenges in a cost-effective manner. Recent advances in fiber optic technology, especially wavelength division multiplexing (WDM), have opened a number of possibilities for designing on-board fiber optic networks for radar and avionics RF signal distribution. In this paper, we investigate a number of different novel ...

The computation capacity of conventional FPGAs is directly proportional to the size and expressive power of Look Up Table (LUT) resources. Individual LUT performance is limited by transistor switching time and power dissipation, defined by the CMOS fabrication process. In this paper we propose OLUT, an optical core implementation of LUT, which has the potential for low latency and low power computation. In addition, the use of Wavelength Division Multiplexing (WDM) allows parallel computation, which can further increase computation capacity. Preliminary experimental results demonstrate the potential for optically assisted on-chip computation.

El continuo crecimiento de la demanda de datos está dirigiendo la investigación para dar luz a una red eficiente en el uso de la fibra óptica y el espectro radioeléctrico. La próxima generación de redes será el resultado de una convergencia entre el dominio óptico e inalámbrico para reunir cada una de sus virtudes en una vasta red de telecomunicaciones más resiliente y más simplificada. Colombia no estará marginada de estos avances ya que actualmente despliega fibra óptica por gran parte del territorio nacional y por tal motivo debe estar informada de los progresos actuales en lo referente a redes de telecomunicaciones de nueva generación y orientar de mejor forma los lineamientos legales del ministerio de TIC (Tecnologías de la Información y las Comunicaciones) para traer en consecuencia grandes beneficios a la regulación de la red interna de telecomunicaciones en cuanto a lo decretado acerca de los inmuebles de propiedad horizontal. En este trabajo se plasman los avances en invest...

This research was conducted to develop a 1×12 optical splitter based on polymer optical fiber (POF) made from polymethyl methacrylate (PMMA) material as a high efficiency optical signal transmission medium. Basically, the optical device has 1 POF input port and 12 POF output ports in a bundled fiber form. There are several system available in the market which are able to split or couple optical signals transmitted into some different channels, which are all afflicted with certain constrains. However, these systems are too expensive for most applications. The goal of this research was to develop an economical splitter for multi-purpose application over PMMA-POF. Red LED with 650 nm wavelength was injected into the splitter with the aim to analyze the power efficiency of the splitter. A coupling efficiency of 80% was demonstrated. The performance of these hand-made splitters can be improved gradually through experience and practice.

Adjustable dispersion-compensation devices with wavelength tunability based on enhanced thermal chirping of fiber Bragg gratings, Photon Technol Lett 15 (2003), 416 -418. ABSTRACT: The effect of channel add/drop response on a new and novel type of narrowband ASE feedback EDFA is investigated. This gain-clamped amplifier utilizes multiple fiber Bragg gratings (FBGs) in a simulated eight-channel WDM network. This experiment demonstrates that in order to minimize variation of surviving-channel power to less then 0.28 dB for channel add/drop, the ASE feedback attenuation level and pump power are critical.

In this paper, an approach of a colorless ONU comprised by a Fabry-Pérot filter and a Semiconductor Optical Amplifier for all-optical clock recovery of the downstream signal, followed by a Mach-Zehnder modulator as the upstream modulator is experimentally demonstrated. The all-optical clock recovery performs data erasure allowing for efficient wavelength reuse of the downstream signal for upstream remodulation. Operation at a fullduplex 10Gb/s symmetrical data rate and 20 dB loss budget is demonstrated over fiber spans of 50 km with achieved power margin of ~8 dB.

Technological improvements, such as erbium-doped fiber amplifiers (EDFAs) and wavelength division multiplexing (WDM), have revolutionized optical transmission, boosting the development and worldwide deployment of the Internet. Similar progress has not yet impacted the routing layer, as current IP routing technology struggles to deliver the necessary bandwidth at competitive costs. Hybrid electro-optical architectures, where dynamical optical circuit switching is combined with legacy packet routing, have been introduced in the past few years as promising solutions to reduce costs at the IP layer and to deliver new revenue-generating services and applications. Most of the architectures currently proposed have focused on end-to-end lightpath provisioning, coordinated through a centralized management plane. In this paper we propose optical IP switching (OIS), a hybrid electro-optical network architecture that combines IP routing and wavelength switching, using a distributed decision-making process. We report technical and economic analysis, based on simulations obtained through real traffic traces and routing tables, that compare our distributed model to an opaque IP-over-WDM and centralized, transparent overlay models. We also report testbed results that analyze the effect of dynamic transparent switching operation on the TCP and UDP transport protocols. The results obtained show that distributed provisioning based on local traffic analysis can be feasible, although more work is required to evaluate the efficacy of optimization techniques on distributed network models.

Optical Networks-on-Chip (ONoC) is emerging technology for future optical interconnects used in all optical networks. The electrical interconnects face lot of problems due to their inability to support higher data rates used in the System-on-Chip (SoC) technologies. Integrated optical interconnects based on SoC avoid this bottleneck with their support to higher data rates. In this paper for the first time we have studied and analyzed ONoC at physical level for the system performance based on crosstalk, BER, throughput, system frequency, and other related parameters. The investigation of ONoC performance is carried out for the multistage microring optical crossconnect on SoC for coherent WDM signals. The analysis can be used in the design of ultra-high speed photonic routers for reliable data communication and processing. The results show the dependency of a coherent crosstalk on the system frequency of SoC and also illustrate the reduction in throughput with increase in number of WDM signals due to higher probability of packet transmission. Minimum 2 dB signal to noise ratio can be obtained when crosstalk is −25 dB with 60 wavelengths for probability of packet transmission is 0.5.

Survivability is a critical concern in modern telecom mesh networks because the failure of a network element may cause tremendous data and revenue loss in such networks using high-capacity optical fibers employing wavelength-division multiplexing (WDM). Multipath provisioning is a key feature of next-generation SONET/SDH networks (which can be used on top of optical WDM), and they can support virtual concatenation (VCAT); thus, multipath provisioning can significantly outperform single-path provisioning in resource efficiency, service resilience, and flexibility. However, in multipath provisioning, differential delay is an important constraint which should be considered. We investigate survivability of service paths based on differential-delay constraint (DDC) and multipath provisioning together in telecom backbone mesh networks. We propose Shared Protection of the Largest Individual Traversed link (SPLIT) method for survivable multipath provisioning, and present a DDC-based algorithm for multipath routing subject to DDC. We also compare the DDC-based algorithm with the K shortest linkdisjoint paths (KDP) algorithm, using SPLIT, under dynamic service requests. We find that exploiting link-disjoint paths is very efficient for survivable multipath provisioning, and our algorithm is resource efficient, has low signaling overhead, and has fast fault-recovery for survivable multipath provisioning with DDC. For a 5 ms DDC, our algorithm can decrease the Bandwidth Blocking Ratio (BBR) significantly in typical US backbone networks.

This paper describes the device, circuit design, and packaging technologies applicable to 40-Gb/s-class future lightwave communications systems. A 0.1-m gate InAlAs/InGa-As high electron mobility transistors (HEMT's) with InP recess etch stopper was adopted mainly for IC fabrication. Fabricated IC's demonstrate excellent data-multiplexing, demultiplexing, and amplifying operation at 40 Gb/s.

Optical network WDM Network design Mixed line rate Maximum transmission range Bit-error rate Channel spacing Launch power Regenerator a b s t r a c t Due to the increasing heterogeneity and the growing volume of traffic, telecom backbone networks are going through significant innovations. Wavelength-division multiplexed (WDM) optical networks can now cost-effectively support the growing heterogeneity of traffic demands by having mixed line rates (MLR) over different wavelength channels.

This paper studies the problem of designing a logical topology over a wavelength-routed all-optical network (AON) physical topology. The physical topology consists of the nodes and fiber links in the network. On an AON physical topology, we can set up lightpaths between pairs of nodes, where a lightpath represents a direct optical connection without any intermediate electronics. The set of lightpaths along with the nodes constitutes the logical topology. For a given network physical topology and traffic pattern (relative traffic distribution among the source-destination pairs), our objective is to design the logical topology and the routing algorithm on that topology so as to minimize the network congestion while constraining the average delay seen by a source-destination pair and the amount of processing required at the nodes (degree of the logical topology). We will see that ignoring the delay constraints can result in fairly convoluted logical topologies with very long delays. On the other hand, in all our examples, imposing it results in a minimal increase in congestion. While the number of wavelengths required to imbed the resulting logical topology on the physical all-optical topology is also a constraint in general, we find that in many cases of interest this number can be quite small.

Continuing increases in efficiency, uniformity, and yield for low-threshold dialectrically Apertured Vertical-Cavity Surface-Emitting Lasers (VCSELs) suggest that this new generation of sources may be ready for insertion into practical parallel interconnect systems. This paper will review the recent evolution of these devices, pointing out key enabling advances and potential roadblocks yet to be addressed. Included will be advances that have led to record low optical losses as well as record high wall-plug efficiency at powers of a few hundred microwatts, desirable for massively parallel optical interconnects. The use of engineered oxide apertures is a key element in these cases. Experimental results will also include recent freespace and WDM fiber interconnects. Remaining issues to be addressed include some sort of lateral carrier confinement, such as a buried-heterostructure, to reduce carrier losses as devices are scaled to small lateral dimensions.

During flight, aircraft avionics transmit and receive RF signals to/from antennas over coaxial cables. As the density and complexity of onboard avionics increases, the electromagnetic interference (EMI) environment degrades proportionately, leading to decreasing signal-to-noise ratios (SNRs) and potential safety concerns. The coaxial cables are inherently lossy, limiting the RF signal bandwidth while adding considerable weight. To overcome these limitations, we have investigated a fiber optic communications link for aircraft that utilizes wavelength division multiplexing (WDM) to support the simultaneous transmission of multiple signals (including RF) over a single optical fiber. Optical fiber has many advantages over coaxial cable, particularly lower loss, greater bandwidth, and immunity to EMI. In this paper, we demonstrate that WDM can be successfully used to transmit multiple RF signals over a single optical fiber with no appreciable signal degradation. We investigate the transmission of FM and AM analog modulated signals, as well as FSK digital modulated signals, over a fiber optic link (FOL) employing WDM. We present measurements of power loss, delay, SNR, carrier-to-noise ratio (CNR), total harmonic distortion (THD), and bit error rate (BER). Our experimental results indicate that WDM is a fiber optic technology suitable for avionics applications.

With standard assumptions the routing and wavelength assignment problem (RWA) can be viewed as a Markov Decision Process (MDP). The problem, however, defies an exact solution because of the huge size of the state space. Only heuristic algorithms have been presented up till now. In this paper we propose an approach where, starting from a given heuristic algorithm, one obtains a better algorithm by the first policy iteration. In order to estimate the relative costs of states, we make a simulation on the fly studying, at each decision epoch, the consequences of all the alternatives actions. Being computationally intensive, this method can be used in real time only for systems with slow dynamics. Off-line it can be used to assess how close the heuristic algorithms come to the optimal policy. Numerical examples are given about the policy improvement.

— Geometric camera calibration, additionally alluded to as camera re sectioning, evaluating the parameters of a lens and picture sensor of a picture. Camera parameters can be utilized to correcting the distortion, and measuring the object size in world unit, or knowing the camera position in the scene. Zhang's calibration method is utilized, the method require a chessboard planner with resolution 1830×1330 pixels to be observed from different orientations and translations also using 2 nd order radial distortion of the polynomial expression. The result shows that lens of longer focal length generate low distortion and it is the better lens as contain minimum value of SSE equal to 3.96426 pixels.

In all-optical networks, signals are transmitted through optical physical layer with no regeneration. Therefore, noise accumulation along lightpath can severely impair optical signal-to-noise ratio. Impairment aware routing and wavelength assignment algorithms (IA-RWA) can take into account these effects, improving the network performance. In this paper we describe a fast and high performance adaptive weight function to be used as the metric for the routing algorithm in optical networks constrained by physical impairments. The input information for this function are link availability, route length and two adjustable parameters. These two parameters provide information about the network impairments. An offline simulation must be run to adjust them prior to the online network operation. The main advantage of this approach is the use of simple network parameters during the routing process instead of a complex optical noise based formulation, which renders it a better performance in terms of both, time to find a route and blocking probability. In our simulations we considered three physical layer effects: ASE noise generation, Optical Amplifier gain and ASE saturation and OXC crosstalk. We performed a performance comparison between this new metric and other metrics previously described in the literature.

We present the results of an investigation of optical gain and noise figure for simultaneous multi-channel amplification of an erbium doped fibre amplifier (EDFA) under optimized pump condition. Different pump configurations with varying input signal levels show interesting features on gain flatness. In the experiment, population inversion along the fibre length which determines the gain-spectra and noise characteristics of the amplifier is adjusted through optimized fibre length and injected pump power in order to minimize the gain-tilt at C-band. It is observed that bi-directional pumping manifests the best combination of low noise and high gain of EDFA which are useful as in-line repeaters in WDM network. We obtain 30 ± 1.5 dB intrinsically flat small signal gain from 1538 nm to 1558 nm band of wavelength with noise figure <4 dB for 16-channel simultaneous amplification in a single stage EDFA without gain flattening filter.

Wavelength division multiplexing (WDM) offers the potential to transport very high bit rates in access systems serving residential and small business customers. We describe the options for WDM access systems, and evaluate them on the basis of an international standard that is emerging for passive optical networks (PON's) that use wavelength-independent power splitting. The greatest impediment to meeting the high-bandwidth potential of WDM for downstream (i.e., from the central office to the home) transmission is the need for a moderately priced multiple-wavelength light source. Implementing WDM in the upstream (home to central office) direction presents greater hurdles than in the downstream. The technical aspects of overcoming these hurdles can all be met. The real challenge will be in finding technical solutions that can meet the very stringent cost requirements of access systems. Systems that use WDM in the downstream direction only, while using wavelength-independent power-combining in a PON configuration for upstream, may prove economical before full WDM systems. WDM may also prove valuable if upgrades are needed in the future for powersplitting PON's.

Passive optical networks (PONs) are being widely considered as a means to implement fiber-to-thehome (FTTH) and deliver broadband access to business and home users. However, technical and consequently regulatory and economic complexities arise in light of their deployment. In this paper, an evaluation of the business prospects of time division multiplexed (TDM) and wavelength division multiplexed (WDM) PON architectures for FTTH deployments under different rollout conditions is performed, based on the ECOSYS techno-economic methodology and tool. The importance of various cost components (fiber installation, optoelectronic components, etc.) is discussed. Using sensitivity analysis, the effect of various parameters such as duct availability, cost of civil works, etc. on the prospects of the investment are investigated. These results reveal several important techno-economic aspects that should be considered by telecom operators, regulators, and policy makers towards a successful FTTH deployment strategy.

This study presents second generation low-cost fused tapered (LFT) 1 × 3 splitter (G2) as novel, low-cost and low-losssplitting device made from PMMA-based polymer optical fiber (POF). G2 (short taper, 0.5 - 2.0 cm) was fabricated byreformulated handwork fusion method using candle and metal tube. A new process, twisting-effect removal, is addeed to refineripple surface in fused input fiber. LED fiber source (wavelength 650) was injected into input fiber while optical power in outputfibers was measured by optical power meter. Insertion loss (7 dB) and excess loss (0.53 dB) for G2 are extremely low. G2 arehomogenous splitters since their splitting ratio are very close to 33:33:33% with ± 5% of tolerance.

This paper focuses on survivable optical networks and studies in detail the network performance improvement that can be achieved when jointly considering network resilience and physical layer constraints. The protection scheme used is path-based shared protection known as backup multiplexing. In the proposed solution routing and wavelength assignment for both primary and protection paths are jointly performed considering their physical performance. Simulations comparing the proposed solution with alternative schemes ...

During lightpath establishment in WDM optical networks, two important steps, other than routing, are: wavelength selection and wavelength reservation. If two or more lightpaths select the same wavelength, wavelength collision occurs. The basic reason for collision is the non-availability of the updated wavelength usage information. Markov based wavelength selection guesses a unique wavelength in advance, where each node periodically broadcasts its adjoining link usage information at a regular interval T. But, at any intermediate time t (0 < t < T), all nodes use the old update which is already outdated by time t. If T is large, the problem becomes severe. To get around this problem without introducing any extra overhead, we propose a novel technique where the normal control packets, passing through the relevant nodes during [0, T ], can be leveraged to carry the desired link state information. This may allow us even to increase the value of T (thereby reducing broadcast overhead), when control packets are frequent in the network. We apply the proposed modification to our previous work on Markov selection Split Reservation Protocol (MSRP) and call the modified protocol Fast updated MSRP (FMSRP). In fast update, we ''piggy-back'' normal control packets with link usage information, in addition to the usual periodic broadcasting of the same at every T. It obviously increases the chance for the nodes to get the latest information of link usage. We have simulated FMSRP and compared it with MSRP and also with another current best protocol (i.e., Markov based Backward Reservation Protocol) to show that the blocking probability for FMSRP improves considerably over them in some regions of offered load.

Abstracf-This paper considers the problem of routing connections in a reeontigurable optical network using wavelength division multiplexing. Each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, such that connections whose paths share a common link in the network are assigned d]fferent wavelengths. We derive an upper bound on the carried traffic of connections (or equivalently, a lower bound on the blocking probability) for any routing and wavelength assignment (RWA) algorithm in such a network. The bound scales with the number of wavelengths and is achieved asymptotically (when a large number of wavelengths is available) by a fixed RWA algorithm. Although computationally intensive, our bound can be used as a metric against which the performance of different RWA algorithms can be compared for networks of moderate size. We illustrate thii by comparing the performance of a simple shortest-path RWA (SP-RWA) algorithm via simulation relative to our bound. We also derive a similar bound for optical networks using dynamic wavelength converters, which are equivalent to circuit-switched telephone networks, and compam the two cases for different examples. Finatly, we quantify the amount of wavelength reuse achievable in large networks using the SP-RWA via simulation as a function of the number of wavelengths, number of edges, and number of nodes for randomly constructed networks as well as deBruijn networks. We also quantify the difference in wavelength reuse between two different optical node architectures. The results show that it is feasible to provide several all-optical connections to each node in a large network using a limited number of wavelengths. For instance, using 32 wavelengths, it is possible to provide 10 full-duplex connections to each node in a 128-node random network with average degree 4, and 5 full-duplex connections per node in a 1000-node random network with average degree 4. The results also show that wavelength converters offer a 10-40% increase in the amount of reuse achievable for our sampling of 14 networks ranging from 16 to 1000 nodes when the number of wavelengths available is small (10 or 32).

This paper describes the device, circuit design, and packaging technologies applicable to 40-Gb/s-class future lightwave communications systems. A 0.1-m gate InAlAs/InGa-As high electron mobility transistors (HEMT's) with InP recess etch stopper was adopted mainly for IC fabrication. Fabricated IC's demonstrate excellent data-multiplexing, demultiplexing, and amplifying operation at 40 Gb/s.

We present a router architecture with electronic queuing and a passive optical multi-channel network, which is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. The AWG's property of spatial wavelength reuse and both fixed-tuned and tunable transceivers enable simultaneous control and data transmission. Our proposed medium access control protocol supports traffic differentiation and utilizes EDF (Earliest Deadline First) to schedule the traffic from input ports to output ports on the router. Our simulations show that the router treats QoS (Quality of Service) traffic well.

Ring architectures have been widely used by telecommunications carriers for the deployment of networks based on synchronous optical network (SONET) and wavelength division multiplexing (WDM). These architectures have several attractive properties that make them desirable for a large number of applications. Even though arbitrary mesh network architectures provide additional degrees of freedom and are more flexible than rings, in a number of applications there are advantages to decomposing the mesh topologies into a set of rings that cover the network. One of the primary uses of ring covers is to provide survivability against link and node failures. This paper investigates novel approaches for establishing ring covers in optical networks with mesh topologies, while minimizing the length of the ring covers.

The protection of service delivery in an integrated network is fast becoming a critical issue. In previous work, we proposed two protection methods, DiffServ and DiffProtect and examined, on a small network, whether DiffServ can be used as a protection mechanism against failures in IP/WDM networks. The results showed that, on average, DiffServ can provide better QoS guarantees than its optical counterpart, DiffProtect. We also found that DiffProtect may perform better than DiffServ under some extreme failure situations so that DiffServ cannot totally replace optical protection in a network but might be able to do so to some degree. We extend these results to larger networks and more complex combinations of protection techniques. We study in this paper a 4-node linear topology and a small 6node mesh network which can be protected by DiffServ, DiffProtect or even a combination of both (MixProtect). Results show that replacing optical protection by DiffServ cannot be done randomly and that the number and position of links protected by DiffServ versus Diff-Protect must be carefully chosen in order to guarantee adequate performance to all traffic types. We explain how this can be achieved with current technology. We also show that the cost of protection using DiffServ is significantly less than that of current methods.

A major building block, which strongly contributes to the contention resolution in OBS networks, is the technique by which a user would access the medium, i.e., the resource that the CP seeks to reserve on each core node. Although the traditional wavelength domain has seemed to be the http://dx.

In all-optical networks, signals are transmitted through optical physical layer with no regeneration. Therefore, noise accumulation along lightpath can severely impair optical signal-to-noise ratio. Impairment aware routing and wavelength assignment algorithms (IA-RWA) can take into account these effects, improving the network performance. In this paper we describe a fast and high performance adaptive weight function to be used as the metric for the routing algorithm in optical networks constrained by physical impairments. The input information for this function are link availability, route length and two adjustable parameters. These two parameters provide information about the network impairments. An offline simulation must be run to adjust them prior to the online network operation. The main advantage of this approach is the use of simple network parameters during the routing process instead of a complex optical noise based formulation, which renders it a better performance in terms of both, time to find a route and blocking probability. In our simulations we considered three physical layer effects: ASE noise generation, Optical Amplifier gain and ASE saturation and OXC crosstalk. We performed a performance comparison between this new metric and other metrics previously described in the literature.

In this work we propose a high-speed hybrid opticaltime-division-multiplexing (OTDM) and wavelength-divisionmultiplexing (WDM) system that seamlessly generates high bitrate data (>200Gbit/s) from a low speed (5Gbit/s) quantum-dot mode locked laser pulse train. The high-speed output data can be generated using electro-optical micro-ring modulators that operate as low as (5Gbit/s). By utilizing time and wavelength domains, the proposed design is a promising solution for highspeed, compact and low-power consumption optical networks on chip.

Wavelength-division multiplexing (WDM) holds great promise for achieving large-scale concurrency on a single fiber. However, standard multichannel approaches have two serious drawbacks when applied to lightwave networks: 1) they require wavelength-agile transmitters or receivers, and 2) pre- transmission coordination between two users wishing to communicate is required. In this paper, we propose a multihop WDM approach, referred to as ShuffleNet, for achieving con currency in distributed lightwave networks. A ShuffleNet can be configured with each user having as few as one fixed-wavelength transmitter and one fixed-wavelength receiver, avoiding both wavelength-agility and pretransmission-coordination problems. Still, the network can achieve at least 40% of the maximum efficiency possible with wavelength-agile transmitters and receivers. To transmit a packet from one user to an other, however, may require routing the packet through intermediate users, each repeating the packet on a new wavelength, until the packet is finally transmitted on a wavelength that the destination user receives. For such a multihop lightwave network, the transmit and receive wavelengths must be assigned to users to provide both a path between all users and the efficient utilization of all wavelength channels. ShuffleNet achieves high efficiency for uniform traffic loads by bringing together generalizations of shuffle interconnection topologies to the problem of wavelength assignment in multihop lightwave networks.

Traffic grooming is an essential functionality of WDM optical networks to provision multi-granularity subwavelength connections. Depending on the number of lightpaths allowed in a connection route, traffic grooming can be classified as single-hop traffic grooming (SH-TG) and multi-hop traffic grooming (MH-TG). MH-TG is more general and resourceefficient than SH-TG, because it allows connections from different source-destination pairs to share the bandwidth of a lightpath. In this paper, we propose a MH-TG algorithm, namely the fixed-order multi-hop (FOMH) grooming algorithm, based on the fixed-alternate routing approach. We introduce the grooming node selection (GNS) problem in MH-TG and propose three grooming policies, namely exhaustive sequential (ES), limited-hop sequential (LHS) and load sharing (LS) policies, to address the GNS problem. Given that the analysis of MH-TG is a relatively unexplored area, we propose an analytical model to evaluate the blocking performance of MH-TG using FOMH and the LS grooming policy. To address the multi-layered routing and multirate connection characteristics of traffic grooming, we introduce a novel multi-level decomposition approach in our analytical model which decomposes traffic at four different levels, namely alternate path, connection route, lightpath and link levels. The Erlang fixed-point approximation method is used to solve the analytical model. Numerical results show that analytical results matches well with simulation results. We also evaluate the effect of the grooming policies, the number of virtual hops (lightpaths) within a connection route and the number of alternate paths on the performance of the grooming algorithm.

We propose and demonstrate employing inverse-return-to-zero (IRZ) downstream signal format to facilitate upstream data remodulation in a wavelength division multiplexing (WDM) passive optical network (PON) architecture with centralized light sources. The finite optical power in each downstream IRZ bit can be simply remodulated by the upstream data at the optical network unit. This can make each downstream and upstream pair share a single light source and such light reuse can be easily realized. An experiment on 10-Gb/s downstream IRZ signal generation, 2.5-Gb/s upstream signal remodulation, and two-way transmission is successfully demonstrated. The downstream/upstream signal performance in such a PON has also been analyzed, which is useful for system design.

The advent of realtime multimedia services over the Internet has stimulated new technologies for expanding the information carrying capacity of optical network backbones. Multilayer wavelength division multiplexing (WDM) packet switching is an emerging technology for increasing the bandwidth of optical networks. Two algorithms for the routing of the multimedia traffic flows were applied: (i) Capacitated Shortest Path First (CSPF) routing, which minimizes the distance of each flow linking the given source and destination nodes and satisfying capacity constraints; and (ii) Flow Deviation Algorithm (FDA) routing, which minimizes the networkwide average packet delay.

This paper investigates transparent wavelength routed optical networks using three different fiber types NZDSF, SMF and PSCF - and validates the effectiveness of Hybrid Raman/EDFA Fiber Amplification (HFA) with different pumping levels, up to the moderate 60% pumping regime. Nodes operate on the basis of flexible-grid elastic NyWDM transponders able to adapt the modulation format to the quality-of-transmission of the available lightpath, exploiting up to five 12.5 GHz spectral slots. Results consider a 37- node Pan-European network for variable Raman pumping level, span length and average traffic per node. We show that HFA in moderate pumping regime reduces the power consumption and enhances spectral efficiency for all three fiber types with particular evidence in NZDSF. In essence to that, introduction of HFA is also beneficial to avoid blocking for higher traffic loads.

Continued progress in both civil and military avionics applications is overstressing the capabilities of existing radio-frequency (RF) communication networks based on coaxial cables on board modern aircrafts. Future avionics systems will require high-bandwidth on-board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fiber optic communication technology can meet all these challenges in a cost-effective manner. Recently, digital fiber-optic ...

A new high capacity switching scheme for ATWWDM networks is presented. The proposed architecture is contention-free, flexible and highly scalable. Switching performance is studied for data rates of up to 10 Gbitlseclport, providing aggregated capacity of over 1 Terabitlsec. Simulation results show that low latency is achieved, yielding a powerful solution for high-performance packet-switch networks.

During flight, aircraft avionics transmit and receive RF signals to/from antennas over coaxial cables. As the density and complexity of onboard avionics increases, the electromagnetic interference (EMI) environment degrades proportionately, leading to decreasing signal-to-noise ratios (SNRs) and potential safety concerns. The coaxial cables are inherently lossy, limiting the RF signal bandwidth while adding considerable weight. To overcome these limitations, we have investigated a fiber optic communications link for ...

An experimental acousto-optic tunable filter that has a narrow spectral bandwidth (0.2 nm at 1550 nm) and a fast (10 psec) tuning capability with a continuous tuning range of 52 nm is described. By combining a conventional diffraction grating with an acousto-optic beam deflector in a transverse configuration, spectral bandwidth has been significantly reduced and the number of usable wavelength channels within the erbium-doped fiber amplifier (EDFA) passband is increased by approximately 20 times. The filter also permits simultaneous and independent selection/routing of many wavelength channels for multi-channel wavelength division multiplexing (WDM) filters/routers/switches or fast scan optical spectrum analyses.

In this paper, we consider two important objectives of network operation: (i) capacity minimization and (ii) revenue maximization. For capacity minimization, we formulate three operational phases in survivable WDM network operation viz., initial call set up, short/medium-term reconfiguration, and long-term reconfiguration. All three phases are derived from a single integer linear programming (ILP) formulation. This common framework incorporates service disruption. We modify the framework for revenue maximization that includes a service differentiation model based on lightpath protection. We propose a multistage solution methodology to solve individual service classes sequentially and combine them to obtain a feasible solution. We provide cost comparisons in terms of increase in revenue obtained by various service classes with the base case of accepting demands without any protection. Results are provided to demonstrate the effectiveness of our framework.