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This paper introduces an optically interconnected distributed shared memory system. The distributed shared memory approach integrates both shared memory and distributed memory system ideas to extract the strengths of each while balancing their respective weaknesses. The system is a system based on a photonic network to support the high communication requirement of . The employs wavelength division multiple access on the photonic network, enabling multiple channels to be formed on a single optical fiber. A result of the high communication capacity is the simplification of the global address mapping problem. This simplified uniform address allocation scheme is introduced. The advantages of the proposed approach are examined through a performance analysis based on a closed queueing network which has been validated through extensive simulation. The performance of the system is evaluated in terms of transaction time of a memory request and system throughput. The impact of variations in the number of channels and processors in the system on these metrics is studied. The effect of variations in memory and channel service times are also evaluated.

The integration of quantum key distribution (QKD) devices with the existing optical fiber networks is of great significance in reducing the deployment costs and saving fiber resources. Wavelength division multiplexing (WDM) is expected to be a desirable approach to fulfill this ultimate task. In this paper, we analyze the dominant noises in WDM-based QKD system and optimize the key parameters based on a modified model with 200 GHz channel spacing. Then, an appropriate decoy-state method is adopted to estimate the system performance considering statistical fluctuations. Finally, a three-layer artificial neural network is used to train and predict the optimal mean photon numbers within different situations. Our work provides a useful method for the parameters optimization of WDM-QKD system and accelerates the practical development of QKD that coexists with the current backbone fiber infrastructure.

Wavelength division multiplexing (WDM) has been emerging as an effective technique for making use of the full bandwidth offered by optical fiber. To achieve long-haul transmission, erbium-doped fiber amplifiers (EDFAs) are employed to compensate for signal attenuation without using optoelectronic/electro-optic conversions. Transmission in these systems is limited by fiber nonlinearities and amplified spontaneous emission noise from amplifiers. In this paper, the long-haul optical WDM system with EDFAs is investigated theoretically. The noise and bit error rate (BER) characteristics of the system with optical amplifiers are calculated and the dependence of the BER on interamplifier separation and input power is shown.

We study the collision-induced timing jitter of optical solitons in dispersion managed wavelength-division multiplexed communication systems. The work presented here is an extension of previous analyzes of two-pulse interactions to the multiple channel case. The numerical study is based on a system of ordinary differential equations obtained using a variational approach that models the evolution of the main parameters of the propagating pulses. We explain the mechanism associated with inter-channel interactions and study the evolution of multiplexed soliton trains and the resulting frequency shift induced jitter as the map strength is varied. The results obtained indicate a strong dependence of the frequency shifts on the position of the channel within the multiplex and the existence of patterns for the frequency shifts that depend on the parity of the number of channels.

A simple distributed "no look-ahead" connection rule with little set-up delay and little control overhead is proposed for interconnection networks representative of all-optical wavelength-routing networks. This connection rule, or call set-up protocol, is designed for networks with installed wavelength changers and supports both dynamic fixed route and dynamic alternative route call set-up. The proposed protocol has near-optimal call set-up probability under the conditions of an elementary route resource model. The protocol also admits explicit analytical expressions for key protocol performance measures, such as call set-up probability and average number of changers used to set up a call.

The recent explosive growth in the Internet technology has made it imperative to have a network which provides a very high bandwidth. Optical networks employing wavelength division multiplexing (WDM) technology are becoming a viable solution to meet this ever-increasing bandwidth demand. Optical burst switching (OBS) networks provide a good solution for a very high traffic influx which is generally bursty in nature. In this, a single control packet is sent for a group of packets which constitute a data burst with a time gap between them to ensure pure optical switching of bursts. Usually bursts that traverse longer paths are more likely to be dropped than those that traverse shorter paths resulting in fairness problem. Fairness means that for all ingress-egress node pairs in a network a burst must have equal likelihood to get through independent of the hop length involved. In this paper, we develop an efficient fairness method to achieve fairness among bursts with different hop counts. The key idea is to collect scheduling statistics by observing the bursts, and based on this information assign different offset time to bursts with different hop counts. Apart from ensuring fairness our method has several attractive features. By using the online statistics, our methods inherently captures the traffic loading patterns and network topological connectivity. It also ensures that the delay experienced by a burst is low and shorter-hop bursts are not over-penalized while improving the performance of longer-hop bursts. We demonstrate the effectiveness of our fairness method through extensive simulation experiments for a number of random networks which differ in the number of nodes and topological connectivity.

We propose a novel bidirectional optical crossconnect (BOXC) using fiber Bragg gratings (FBGs) and optical circulators. Dynamic control for wavelength routing is achieved by employing tunable FBGs. Because only a few optical circulators are used, the proposed BOXC is more cost-effective than previously reported BOXCs. Our preliminary study shows that the proposed BOXC has potentially small insertion loss and low crosstalk. It requires a small tuning range equal to wavelength channel spacing for tunable FBGs. We show that a large BOXC can be built based on the Benes network structure and present a method to reduce the complexity.

We propose a new reconfigurable add-drop multiplexer using tunable fiber Bragg gratings (FBGs) and optical circulators. The new OADM allows dropping several fixed wavelength channels and at least one tunable wavelength channel. By properly assigning wavelengths channels that are add-dropped at an OADM node, the tuning range required for tunable FBGs can be made as small as the channel spacing. The proposed OADMs have potentially low insertion loss. The operation and performance of this OADM are experimentally investigated.

The performance of an optical wavelength division multiplexed system is analyzed including the effect of four wave mixing (FWM) in presence of chromatic dispersion. FWM process in the single mode fiber as well as in the fiber amplifier is taken into account. It is observed that the efficiency of FWM generation can be greatly reduced by simultaneously making the spacing between channels unequal and by employing nonuniform chromatic dispersion along the fibers in the communication link. The power limitations are evaluated under various conditions of system parameters. The power depletion is compared under different channel spacing schemes.

Wavelength division multiplexing (WDM) networks have become a viable solution to meet the increasing bandwidth demand. These networks carry messages in the optical domain at data rates of several Gb/s. Such high data rates make it necessary for using efficient restoration protocols in an event of a failure. This paper addresses the problem of dynamic path-based restoration in WDM optical networks. Our objective is to develop a protocol that ensures rapid recovery while keeping the restoration ratio high. We propose two distributed dynamic restoration protocols called disjoint path-wavelength grouping protocol and disjoint weighted path-wavelength grouping protocol. Both these protocols group all the candidate backup paths of the failed paths into path-disjoint groups before assigning wavelengths to them. This allows the failed paths to search different sets of wavelengths on various candidate backup paths in parallel without any reservation conflicts. Also, it does not require any reservation retries, thus resulting in rapid restoration. The grouping method attempts to restore increased number of failed paths by allowing increased number of wavelengths to be searched on a path. The performance of the proposed protocol is verified through extensive simulation experiments.

An improved model is proposed to approximate the actual Raman gain profile of silica, which in turn is used to calculate the power depletion of the shortest-wavelength channel due to all other channels in the system. In this improved model, the stimulated Raman scattering (SRS) effects from channels at the tail of Raman gain profile are taken into account. A statistical analysis is done for the SRS crosstalk in a wavelength division multiplexed system including modulation statistics. The bit error rate and power penalty are estimated, where the improved model for the Raman gain spectrum is used.