Xu Anshi

A Novel Burst Assembly Algorithm for OBS networks -- Based On Data-length Time-lag Product

Traditional burst assembly algorithms are mostly timer-based and length-based in optical burst switching (OBS) networks. In this paper, a novel data burst generation algorithm is presented. By using the product of assembled data length and its arrival time lap as burst assembly threshold, data-length time-lag product (DTP) assembly algorithm exhibits combination characteristics of the timer-based and length-based assembly algorithm in OBS networks. Through simulation with Poisson arrival traffic model, the proposed method is compared with timer-based and length-based assembly algorithms respectively. The simulation results show that this algorithm can adaptively change the data burst size according to the offered load and present a more acceptable delay

Parallel link server architecture: a novel contention avoidance mechanism in OBS networks

Optical burst switching (OBS) is thought to be the best way to adapt bursty traffic of IP-based next generation network services. However, there are a lot of challenges to make OBS networking a reality. Of most concern is burst contention avoidance. The major contention avoidance resolutions in literature are wavelength conversion, fiber delay lines, and deflecting routing. They are very vulnerable to network load and may suffer from severe data loss in case of heavy traffic. Even at moderate traffic, contention caused by using these methods lead to burst blocking and data losses. In this article, a novel contention avoidance technique is presented by using the parallel link server (PLS) architecture, which may overcome the lack of information at the edge node and the absence of global coordination among nodes. Using Poisson and Self-Similar traffic arrival models, the proposed mechanism is compared with the traditional single link server architecture through simulation in the 14-node national science foundation network. The numerical results show that this architecture, without additional other methods, can obtain burst blocking and data dropping probabilities with almost two orders of magnitudes less than those in the single link server architecture. Gains are achieved by less than 7% increase in end-to-end delay when carrying coordinated traffic and a load under 0.45.

Plasmonic Corrugated Horn Structure for Optical Transmission Enhancement

We propose and theoretically analyze a plasmonic corrugated horn structure for enhanced optical transmission. It makes use of the enhancement of unidirectional propagating surface plasmon polaritons at oblique incidence. Geometric parameters such as the groove depth and width are optimized. Analysis shows that it presents a better performance than the bulls eye structure for a small number of grooves.

High speed integrated acousto-optic switch with high extinction ratio

The technology of single phase unidirectional transducer and focused transducer was adopted for the design of acousto-optic switch. The extinction ratio up to 32 dB and switching speed at 300 ns was achieved.

A Novel Architecture for Metropolitan Area Networks

A novel architecture, dual-fiber-link optical burst switching which has the similar functions of fiber-delay-lines, partial wavelength-converter, and deflection-routing, is proposed for MAN. Results show that it can exponentially decrease burst blocking probability.

Ultra-Long Haul L-Band WDM Transmission over a Standard Single-Mode Fibre Loop Using DCF+CFBG Hybrid Dispersion Compensation

We demonstrate a 10.7 Gb/s-line-rate L-band wavelength-division-multiplexer (WDM) loop transmission over a 1890-km standard single-mode fibre (SSMF) with a 100-km amplifier spacing as well as non-return-to-zero (NRZ) format. The dispersion compensating fibre (DCF) plus chirped fibre Bragg grating (CFBG) is employed for hybrid inline dispersion compensation. The power penalty of each channel is less than 3 dB after three-loop transmission. The experimental results show that high-performance CFBGs can be successfully used in ultra-long haul (>1000 km) WDM systems. We also point out that the all-CFBG compensation scheme is not suitable for re-circulating loop transmissions.

A New Family of 2-D Optical Orthogonal Codes for Optical CDMA Access Networks

A new family of 2-D OOC, PC/OOC, for use in optical CDMA access networks is proposed in this paper. Analysis of its auto-and-cross correlation property is given and proof of that its cardinality achieves the upper bound in theory is presented. In contrary to previously constructed codes, PC/OOC exhibits the characteristics that the construction algorithm is simple and the number of wavelengths is optional which makes PC/OOC truly applicable to OCDMA networks as multi-access codes and greatly facilitates the operation of OCDMA

Performance analysis of multi-fiber WDM network with limited-range wavelength conversion

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength conversion technology and wavelength converters play an important role in enhancing fiber utilization and in reducing the overall call blocking probability of the network. In this paper, we develop a new analytical model to calculate the average blocking probability in multi-fiber link networks using limited-range wavelength conversion. Based on the results obtained, we conclude that the proposed analytical model is simple and yet can effectively analyze the impact of wavelength conversion ranges and number of fibers on network performance. Also a new heuristic approach for placement of wavelength converters to reduce blocking probabilities is explored. Finally, we analyze network performance with the proposed scheme. It can be observed from numerical simulations that limited-range converters placed at a few nodes can provide almost the same blocking probability as full range wavelength converters placed at all the nodes. We also show that being equipped with a multi-fiber per-link has the same effect as being equipped with the capability of limited-range wavelength conversion. So a multi-fiber per-link network using limited-range wavelength conversion has similar blocking performance as a full wavelength convertible network. Since a multi-fiber network using limited-range wavelength conversion could use fewer converters than a single-fiber network using limited range wavelength conversion and because wavelength converters are today more expensive than fiber equipment, a multi-fiber network in condition with limited-range wavelength conversion is less costly than a single-fiber network using only limited-range wavelength conversion. Thus, multi-fiber per-link network using limited-range wavelength conversion is currently a more practical method for all optical WDM networks. Simulation studies carried out on a 14-node NSFNET, a 10-node CERNET (China Education and Research Network), and a 9-node regular mesh network validate the analysis.

43 Gb/s DWDM Optical Transmission System Using NRZ Format and Electro-absorption Modulation

We demonstrate experimentally a 43 Gb/s DWDM optical transmission system over 900 km single mode fiber with 100 km spans using NRZ format and Raman amplification without FEC. A commercial LiNbO3 modulator and a self-designed 43 Gb/s transmitter based on electro-absorption modulator and are compared in the system, and for the first time the electro-absorption modulation is shown to be able to realize up to 1200 km transmission with a power penalty less than 2 dB. This system includes 8 channels of 43 Gb/s DWDM signal and can support 40 channels over C band. Transmission over 1500 km is also presented and the influence of polarization mode dispersion is shown to be a main limitation.

Novel Optical Filters Configuration for Dispersion Compensation in High-Speed WDM Optical Communication Systems

Two new configuration of optical all-pass filters used for tunable dispersion compensation in high-speed WDM optical communication systems are described, one of which is based on an asymmetry Mach-Zehnder (MZI) and an optical fiber delay line; and the other is based on an asymmetry MZI and a ring resonator. A two-stage device is demonstrated with FSR of 100 GHz, the former structure has a dispersion tuning range of plusmn50 ps/nm,a passband width of 70 GHz,and the group delay ripple less than 2.7 ps. The latter structure has a dispersion tuning range of plusmn100 ps/nm,a passband width of 75 GHz,and the group delay ripple is less than 2.3 ps