Gail R. Lalk

Laser direct writing of channel waveguides using spin‐on polymers

A focused argon‐ion laser beam (λ=350 nm) is used to fabricate optical channel waveguides on oxidized silicon wafers using a commerically available spin‐on polymer. The polymerization process is photon induced, thus allowing the reaction to occur in a room‐temperature ambient. This allows the fabrication of waveguides on a variety of substrates including those with low melting points. The losses in these waveguides are typically less then 1 dB/cm, making them applicable to a variety of optical interconnect problems. In particular, we demonstrate their use in the fabrication of an optical power tap.

Radiant cured polymer optical waveguides on printed circuit boards for photonic interconnection use

We report a simple technique for patterning channelized optical waveguides on standard electronic printed circuit card material. The technique exploits the abundance of transparent, radiant-curing polymer adhesives in the fiber optics and the dental industries. The process is compatible with standard printed circuit card fabrication processes; hence its applicability to optical interconnection scenarios. We report typical guide losses in the 0.4-0.6-dB/cm range. Measurements were made using an automated noninvasive, nondestructive technique, also briefly described here. Simple structures, such as splitters, bus lines, and 90 degrees bends were fabricated and are described. Optical coupling to the waveguides from packaged devices is also discussed.

Efficient data reconciliation

Abstract Data reconciliation is the process of matching records across different databases. Data reconciliation requires “joining” on fields that have traditionally been non-key fields. Generally, the operational databases are of sufficient quality for the purposes for which they were initially designed but since the data in the different databases do not have a canonical structure and may have errors, approximate matching algorithms are required. Approximate matching algorithms can have many different parameter settings. The number of parameters will affect the complexity of the algorithm due to the number of comparisons needed to identify matching records across different datasets. For large datasets that are prevalent in data warehouses, the increased complexity may result in impractical solutions. In this paper, we describe an efficient method for data reconciliation. Our main contribution is the incorporation of machine learning and statistical techniques to reduce the complexity of the matching algorithms via identification and elimination of redundant or useless parameters. We have conducted experiments on actual data that demonstrate the validity of our techniques. In our experiments, the techniques reduced complexity by 50% while significantly increasing matching accuracy.

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. >

Relaxed-tolerance optoelectronic device packaging

The authors present an approach to single-mode fiber coupling which results in relaxed alignment tolerances during the package assembly process. The authors use a ball lens to couple from the optical device either directly to single-mode fiber (SMF), or indirectly to SMF through a fiber lens. The ball lens is aligned and mounted in the first assembly stage. The lens is aligned and fixed either mechanically or semiactively. In the second stage of assembly, the SMF is aligned so as to compensate for any small misalignments of the ball lens. The authors have achieved coupling efficiencies of 33-40 % with this coupling scheme. It has been used for coupling to standard laser diodes and to near-traveling wave optical amplifiers. Fiber-to-fiber gains of 8.5-10 dB have been achieved with packaged devices. The approach provides some versatility with respect to the placement of passive optical components inside the package. >

Improving Data Quality in Practice: A Case Study in the Italian Public Administration

Assessing and improving the quality of data stored in information systems are both important and difficult tasks. For an increasing number of companies that rely on information as one of their most important assets, enforcing high data quality levels represents a strategic investment aimed at preserving the value of those assets. For a public administration or a government, good data quality translates into good service and good relationships with the citizens. Achieving high quality standards, however, is a major task because of the variety of ways that errors might be introduced in a system, and the difficulty of correcting them in a systematic way. Problems with data quality tend to fall into two categories. The first category is related to inconsistency among systems such as format, syntax and semantic inconsistencies. The second category is related to inconsistency with reality as it is exemplified by missing, obsolete and incorrect data values and outliers.In this paper, we describe a real-life case study on assessing and improving the quality of the data in the Italian Public Administration. The domain of study is set on taxpayers data maintained by the Italian Ministry of Finances. In this context, we provide the Administration with a quantitative reckoning of such specific problems as record duplication and address mismatch and obsolescence, we suggest a set of guidelines for setting precise quality improvement goals, and we illustrate analysis techniques for achieving those goals. Our guidelines emphasize the importance of data flow analysis and of the definition of measurable quality indicators. The quality indicators that we propose are generic and can be used to describe a variety of data quality problems, thus representing a possible reference framework for practitioners. Finally, we investigate ways to partially automate the analysis of the causes for poor data quality.

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.

Photo-Polymerized Acrylic Waveguides for Optical Interconnects

We have fabricated acrylic based optical channel waveguides using proximity photolithography as well as laser direct writing. The cladding layer is a photosensitive aliphatic urethane dimethacrylate and the guiding layer is a photosensitive aromatic acrylated epoxy. This material system provides good adhesion to a variety of substrate materials. Since both the guiding and cladding layers are applied, these materials can be employed in several electrical/optical applications including multi-chip modules using Si, SiO 2 , and polyimide as well as high speed electronic board technologies using teflon based substrates. Loss measurements show a guide loss of less than 0.08 dB/cm for multi-mode waveguides fabricated using the direct write laser technique. Lithographically defined guides have a loss of 0.3 dB/cm for similar size waveguides.

Board Level High Speed Photonic Interconnections: Recent System Developments

The device requirements and system design issues for board-level optical links differ from their counterparts in optical links used for longer distance communications. We have fabricated a research prototype of a board-level optical link which is designed to operate in a high-speed digital equipment internal interconnect environment. The experimental transmitter and receiver packages are specifically designed for subminiaturized applications. We have explored the use of photolithographically patterned waveguides made of polymers as an alternative to the use of fiber at the board level. The major aspects of the device design are reviewed, but the emphasis of this paper is the systems-level design issues. We will discuss the design goals and the performance of the link. The results of this work demonstrate the feasibility of optics for signal distribution at the board level.

Board Level High Speed Photonic Interconnections: Recent Technology Developments

Board level photonic interconnections offer the potential of enhancing standard high speed electronic systems performance. But, to be successful, significant advances in optoelectronics packaging, physical design and subminiaturization are necessary. This paper addresses these physical design issues. Solutions currently being researched are presented. Technology advances in transmitter, receiver, and optical channel development are reported.