Dennis L. Karst

Low-cost fabrication of optical subassemblies

The optical subassembly is a major contributor to the cost of a fiberoptic computer data link. A technology for low-cost fabrication of optical subassemblies is described, with emphasis on the transmitter subassembly. A factor of three cost reduction is achieved by limiting the parts count to only three: a laser or receiver chip packaged in a TO-can, a plastic housing, and a plastic aspheric lens; and by employment of a fast, automated active-alignment and subsequent fixing technique. Key enabling features include the rise of precision injection molding of specially chosen plastics, an aspheric lens design which permits wide positional variations in the axial direction, and curing of a fast setting epoxy through the use of RF power. A tool was constructed which produced subassemblies at high yield having satisfactory performance.

CD laser optical data links for workstations and midrange computers

The Optical Link Card (OLC) is a high speed fiber optic data link developed for low cost computer interconnect applications. Several versions of this OLC family are now in volume production. They incorporate a short-wavelength, CD-type laser source, high-density surface mount (SMT) packaging, and a novel technique to comply with worldwide laser safety regulations. The current cards, operating at 220 Mb/s and 266 Mb/s over 2 km of multimode optical fiber, provide compatibility with the emerging ANSI standard called Fiber Channel. Future extensions, especially to higher data rates, are being developed to meet the computer users growing demand for higher bandwidth networking solutions.<<ETX>>

Evolution of optical subassemblies in IBM data communication transceivers

Optical subassemblies (OSAs) are the highest-cost component of datacom transceivers, and therefore the component that is most constrained by production cost concerns. While transceiver costs have declined, operating rates have increased from 266 Mb/s to 10.3 Gb/s. Corresponding OSA designs, based on multimode fiber, have evolved incrementally through several generations, to 2.4 Gb/s. Costs have been lowered in successive generations by reducing the number of parts, material costs, and complexity of assembly, and by using lower-cost optoelectronic devices--vertical-cavity surface-emitting lasers (VCSELs). This paper traces the mechanical aspects of OSAs that have been developed and introduced into products or developed as demonstration projects.

Optical data link using a CD laser

A 266 Mb/s optical link card based on a 780 nm compact disc (CD) laser has been designed by IBM Rochester to provide a fast data link for interconnecting computer systems. This design not only met the performance and cost objectives of the data communications environment, it also overcame key challenges in the areas of laser safety, laser reliability, and modal noise. The 266 Mb/s data rate was selected to conform to the new American National Standard Institute (ANSI) Fiber Channel Standard (FCS).

CD Laser As A Fiber Optic Source For Computer Data Links

Computer data links are evolving from copper cable systems to fiber optics simply because the optical fiber itself offers the advantages of higher data rates and longer distances. The Compact Disc (CD) laser is suitable as the light source because it satisfies the computer system requirements for low cost, high data rate, miniaturized package, and high reliability.