Zhang Mingde

A modified split-step Fourier method for optical pulse propagation with polarization mode dispersion

A modified split-step Fourier method (SSFM) is presented to solve the coupled nonlinear Schrodinger equation (CNLS) that can be used to model high-speed pulse propagation in optical fibres with polarization mode dispersion (PMD). We compare our approach with the SSFM and demonstrate that our approach is much faster with no loss of accuracy. We discuss the pulse distortion and system Q-factor of non-return-to-zero (NRZ), return-to-zero (RZ) and pre-chirped RZ (CRZ) formats in the presence of high PMD through this approach. The simulation results show that CRZ pulses are the most tolerant to high PMD values and the extinct ratio has a great impact on the transmission performance.

Connectivity reliability evaluation for optical layer in IP over WDM networks based on minimal path sets

Reliability evaluation of communication network is the precondition of researching how to provide various traffic QoS (quality of service) guarantee. This paper presented an evaluation method for WDM (wavelength division multiplexing) optical layers connectivity reliability. First, we calculated all the minimal path sets of source-destination node pairs in the network using optimized node-traversal method and direct disjoint method according to adjacency matrix and network structure parameters matrix, then obtained connectivity reliability of source-destination node pairs through probability solution, furthermore, MTBF (mean time between failures) and failure frequency of the network were figured out. Simulation on CERNET, NSFNET and MESH-TORUS network showed that connection reliability of the MESH-TORUS is higher than that of the former two. Data results based on this method is an important reference of integrated reliability evaluation for the whole optical networks

An optical fiber industrial network with high availability

An optical fiber industrial network is the key to data exchange between upper administration layer and lower control layer. A high-speed network can realize all kinds of data, such as control commands, field signals and multimedia signals, to be transferred together. Good availability is the basis of ensuring optical fiber industrial network normal running. By analyzing the multi-level single-attachment network availability, the conclusion is that a dual-level single-attachment network is the best topology of the optical fiber industrial network. Finally, the application of this network in a transformer substation is introduced.

A novel fuzzy evaluation method to evaluate the reliability of FIN

Based on fuzzy theory, we present the novel concept that a complex system should be described with multiple state linguistic terms (SLT). A network performability index given, the reliability indices of the object with multiple working-state are defined for the first time. On the grounds of linguistic cloud model (LCM), a fuzzy evaluation method for the network reliability is introduced. The method is used to examine the reliability of the fiber industry network (FIN) by way of Monte Carlo simulations. The results for FIN show that the method is efficient for reliability evaluation of industrial control networks thus can be used as a tool to design highly reliable industry networks.

A novel model on dynamic resource allocation in optical networks

A novel model on dynamic resource allocation in the WDM optical networks is proposed, basing on the integrated considerations of the impacts of transmission impairments and service classification on dynamic resource allocation in the optical layer. In this model, the priorities of optical connection requests are mapped into different thresholds of transmission impairments, and a uniform method which is adopted to evaluate the virtual wavelength path (VWP) candidates is defined. The Advanced Preferred Wavelength Sets Algorithm (A-PWS) and the heuristic Dynamic Min-Cost & Optical Virtual Wavelength Path Algorithm (DMC-OVWP) are presented addressing the routing and wavelength assignment (RWA) problem based on dynamic traffic and multi priorities in wavelength-routed optical networks. For a received optical connection request, DMC-OVWP is employed to calculate a list of the VWP candidates, and an appropriate VWP which matches the request’s priority is picked up to establish the lightpath by analyzing the transmission qualities of the VWP candidates.

Three-dimensional beam propagation method based on the variable transformed Galerkin’s method

A novel three-dimensional beam propagation method (BPM) based on the variable transformed Galerkin’s method is introduced for simulating optical field propagation in three-dimensional dielectric structures. The infinite Cartesian x-y plane is mapped into a unit square by a tangent-type function transformation. Consequently, the infinite region problem is converted into the finite region problem. Thus, the boundary truncation is eliminated and the calculation accuracy is promoted. The three-dimensional BPM basic equation is reduced to a set of first-order ordinary differential equations through sinusoidal basis function, which fits arbitrary cladding optical waveguide, then direct solution of the resulting equations by means of the Runge-Kutta method. In addition, the calculation is efficient due to the small matrix derived from the present technique. Both z-invariant and z-variant examples are considered to test both the accuracy and utility of this approach.

Design of buffer structure at core nodes in optical burst switching

Reasonable and effective buffer structures are proposed in core routers/nodes of optical burst switching. Based on the model of burst traffics and their contentions, the basic qualifications for the design of buffer structures are concluded. With these qualifications, buffer and switch integrated structures are proposed; and by conclusion and expansion, the classification rules of buffer structures are also proposed from different angles. The schemes to integrate structures are analyzed and simulated.

Full-vectorial analysis of optical waveguides by the finite difference method based on polynomial interpolation

Based on the polynomial interpolation, a new finite difference (FD) method in solving the full-vectorial guided-modes for step-index optical waveguides is proposed. The discontinuities of the normal components of the electric field across abrupt dielectric interfaces are considered in the absence of the limitations of scalar and semivectorial approximation and the present FD scheme can be applied to both uniform and non-uniform mesh grids. The modal propagation constants and field distributions for buried rectangular waveguides and optical rib waveguides are presented. The hybrid nature of the vectorial modes is demonstrated and the singular behaviours of the minor field components in the corners are observed. Moreover, solutions are in good agreement with those published early, which tests the validity of the present approach.

Novel strip EAM with a ring resonator on InP/InGaAsP-MQW

This article describes the three-dimension time domain method employed as simulation instrument to design the strip EAM with a ring resonator on InP/InGaAsP-MQW. The 3D-FDTD arithmetic is applied, and PML (perfectly matched layer) absorption boundary layer is designed in the premise of satisfaction of stability and constringency of the iteration. The main testing equipment is the optical spectral analyzer. PIC is the key chip unit that forms the future optical communication system with high reliability and stability, optical information processing system, optical surveying system.

Performance of OCDMA spectral-amplitude-coding with optical orthogonal codes

The scheme of FBG-based OCDMA spectral-amplitude-coding (SAC) and the designing of SAC encoder/decoder with the (N, w, /spl lambda/) = (q/sup 2/ + q + 1.q + 1.1) optical orthogonal codes are discussed. The performance of this system, especially the SIR and BER resulting from multi-access interference (MAI) are also analyzed in detail.