Sarry F. Habiby

Physical design issues for very large ATM switching systems

The authors examine the physical design issues associated with terabit/second switching systems, particularly with regard to the customer access portion of the switch. They determine the physical design requirements in the areas of backplane interconnections, integrated circuit packaging, and circuit board technology and identify areas where existing- or near-future physical design technologies are inadequate to meet the requirements of this application. A new 3D interconnection architecture that solves some of the problems encountered at the backplane level is suggested. It is also suggested that multichip module technology will help meet some of the speed and density requirements at the chip packaging level. Some of the system-level consequences of the proposed model are discussed. >

Dynamic holographic interconnects with analog weights in photorefractive crystals

A photorefractive interconnect system with coherently erasable synapses (PISCES) is described. Comparing holographic erasure by intensity and phase modulation of the writing beams, we find that the timeaverage technique is most amenable to system implementation. Calculations derived from a simple model of diffraction show that it is possible to find configurations that maximize the interconnection capacity. The PISCES includes Fresnel zone plates for spot array generation, amplitude and phase spatial light modulators based on liquid crystal technology, and detector arrays, in addition to the photorefractive crystal. Alternatives for each of these elements are described.

Automatic Identification of Impairments Using Support Vector Machine Pattern Classification on Eye Diagrams

We have demonstrated powerful new techniques for identifying the optical impairments causing the degradation of an optical channel. We use machine learning and pattern classification techniques on eye diagrams to identify the optical impairments. These capabilities can enable the development of low-cost optical performance monitors having significant diagnostic capabilities

Simulation of ASE noise accumulation in a wavelength add-drop multiplexer cascade

This letter presents a computer simulation of a cascade of wavelength add-drop multiplexers (WADMs) each consisting of optical amplifiers, a multiplexer/demultiplexer pair, gain equalizing attenuators and 2/spl times/2 optical switches. It is shown that one of the eight wavelengths can propagate through more than 50 equidistant WADMs in a wavelength-division multiplexed (WDM) optical network before its optical signal-to-noise ratio (SNR) drops below acceptable levels. These simulations indicate that a national scale transparent WDM network is feasible.

WDM Optical Backbone Networks in aircraft applications: Networking challenges and standards progress

The benefits of introducing optical networks in aircraft applications and an overview of related networking challenges are presented in this paper. Progress in the development of WDM-based Optical Backbone Networks (OBN) standards for aircraft networks is also reviewed. Optical networks can enable flexible, high bandwidth, low cost, and low weight communication links on aircraft platforms spanning military and commercial applications. This paper highlights networking challenges (architecture, systems and technology) associated with optical networks, and delineates opportunities for fiber optic systems in aircraft platforms through a case study comparing copper-based and fiber-based cable infrastructure. The paper also presents the status of standards development by the SAE International Avionics Systems Division (ASD) AS-3 WDM LAN working group.

Wavelength-domain simulation of multiwavelength optical networks

This paper presents an efficient simulation method for the design of the optical transport layer of large-scale multiwavelength optical networks. According to this method, computations are performed in two complementary steps. During the first step, the powers of optical signals, amplified spontaneous emission (ASE) noise, and linear optical crosstalk are calculated at all points in the network. During the second step, the distortion and the overall performance of selected optical paths in the network are calculated. Each simulation step requires a different computer representation of optical signals and network components. A large part of this paper is devoted to the description of the wavelength-domain representation used during the first simulation step. In wavelength domain, optical signals are represented by their carrier wavelength and average power, exclusively. In addition, the network components are fully characterized by their loss or gain as a function of wavelength. The phase-transfer functions of the network components are discarded. These simplifications result in a dramatic increase in execution speed. During the second simulation step, optical signals are represented by their temporal waveforms. Linear optical network segments are replaced by an equivalent channel. The link between the two simulation steps is explained in detail. The remainder of the paper is devoted to the implementation of a network simulation tool based on the above method in the context of the multiwavelength optical networking (MONET) project. To illustrate the capabilities of the MONET simulator, a mesh of 4/spl times/4 wavelength-selective cross-connects (WSXCs) and wavelength add-drop multiplexers (WADMs) is studied and the crosstalk performance is determined.

Ronia results: WDM-based optical networks in aircraft applications

This paper reviews the results of the Requirements for Optical Networks in Avionics (RONIA) project providing motivation for the use of WDM-based optical networks in aircraft applications and highlights challenges to be addressed.

OCDM-Based All Optical Multi-Level Security

Faced with the demand for high capacity communication in avionics there is growing interest to deploy fiber optic networks. With the introduction of optics in avionics, an optical physical layer that can support multilevel security (MLS) is needed. Using different fibers (space division multiplexing) is an obvious choice. In wavelength division multiplexing (WDM) networks, different security levels are carried through different optical windows. However, WDM enabled MLS is susceptible to eavesdropping through inter-window cross talk. Recently we introduced a new concept of OCDM methodology based on a passive spectral phase encoding (SPE) scheme that is compatible with WDM networks and offers photonic layer security (PLS). This compatibility is achieved through the ability to access and modify optical phase of tightly spaced phase locked laser lines with high resolution. The next level of MLS beyond WDM is offered by providing the proper recipient its unique OCDM code, without which inadvertent leakage of signal cannot be deciphered. A higher level of security that is robust to both exhaustive search and archival attacks can also be offered through phase scrambling of the inverse multiplexed tributaries of the high data rate aggregate signal. In this presentation we summarize our all optical passive OCDM methodology that has been studied for terrestrial WDM networks and underline its size, weight and power (SWaP) figures of merit for MLS in avionics.

Potential roles of optical interconnections within broadband switching modules

An investigation of potential physical design bottlenecks in future broadband telecommunication switches has led to the identification of several areas where optical interconnections may play a role in the practical realization of required system performance. In the model used the speed and interconnection densities as well as requirements for ease-of-access and efficient power utilization challenge conventional partitioning and packaging strategies. Potential areas where optical interconnections may relieve some of the physical design bottlenecks include fiber management at the customer interface to the switch routing and distribution of high-density interconnections within the fabric of the switch and backplane interconnections to increase system throughput.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

WDM standards: a first impression

Wavelength Division Multiplexing (WDM) technology can be used to create high-capacity, rearrangeable, survivable networks for the transport of broadband services. A key factor in the successful commercialization of multi-wavelength optical networks is the availability of standards for WDM point-to-point and optical networking transmission systems. International standards recommendations are currently being formulated in the ITU (formerly CCITT) in a number of Study Groups related to multiwavelength transmission systems. In this paper, a review will be presented on the status of the recommendations in the current study period, focusing on point-to-point OC-48 WDM systems. Transmission signal parameters such as reference frequency, frequency spacing, and optical signal power levels, as well as optical supervisory channel specifications are being addressed currently. A future set of specifications related to optical networking systems will be addressed in the study period extending from 1997 to 2000.