Jeannine M. Trewhella

Chip-to-chip optical interconnects

Terabus is based on a silicon-carrier interposer on an organic card containing 48 polymer waveguides. We have demonstrated 4times12 arrays of low power optical transmitters and receivers, operating up to 20 Gb/s and 14 Gb/s per channel respectively

Package design and measurement of 10 Gbps laser diode on high-speed silicon optical bench

In this paper the electrical package design for a 10 Gbps laser diode on a silicon optical bench will be presented. Specifically the wideband impedance matching is addressed. Simulated data will be compared to measurements.

Total internal reflection mirrors fabricated in polymeric optical waveguides via excimer laser ablation

Excimer laser (248 rim) ablation has been used for rapid large area defmition of total internal reflection (TIR) mirrors in thick (50 tim) polymeric optical waveguides. The mitrors are capable of reflecting light into or out of the waveguide plane with a loss of less than 1 dB

Propagation properties in short lengths of rectangular epoxy waveguides

The propagation loss and beam spreading in large-core epoxy ridge waveguides on a glass substrate at wavelengths ranging from 630 to 1550 nm have been measured. At the intermediate wavelengths, a loss floor of 1.2 dB/cm is observed which is caused by inclusions and wall imperfections. The theoretical and experimentally determined equilibrium numerical aperture is 0.65 and 0.29 and the modal dispersion is 5.1 and 1.0 ps/cm, respectively. The discrepancy is due to strong scattering. The scattering does not give rise to any noticeable mode mixing. The epoxy waveguides also provide a rapid filling of the modes which is attractive for modal noise suppression.<<ETX>>

Direct VCSEL launch into large-core multimode fiber: enhancement of the bandwidth x distance product

Traditionally, large core (greater than 100 micron) step index multimode optical fiber has occupied a reactively small niche of applications in data communications. While the large diameter of this type of fiber makes it easy to align to optoelectronic devices, its bandwidth*distance (BW*D) product is low due to modal dispersion between the large number of modes supported by a fully filled fiber. Recently, interest has been renewed in using an underfilled launch to excite 62.5 micron core graded index multimode fiber as a way to improve its bandwidth performance. With the proper launch conditions, this same effect has been measured in large core fiber. A vertical cavity surface emitting laser (VCSEL) is used to provide a low numerical aperture launch into a large core fiber, which has a relatively large numerical aperture. The laser thus underfills the modes of the fiber, and a bandwidth enhancement for the fiber is obtained. Results of experiments performed on step and graded index large core multimode fibers using a direct VCSEL launch are presented. In addition, these relaxed alignment tolerance fibers allow the utilization of very low cost cabling and connectorization procedures for parallel optical fiber cables. Data, including skew, bandwidth, and insertion loss, are presented on these cables.

How detrimental could a via be

The vertical interconnects used in printed circuit boards, known as vias, are becoming increasingly critical to interconnect performance with ever increasing system data rates. To explore the effects of vias on system link performance, both simulations and measurements on test structures were implemented in a wide frequency range. The results indicate that proper via management is vital to the success of interconnect designs operating at multi-Gb/s data rates.

Comparison of low-cost fiber optic technologies for data transmission

This paper presents a comparison of technologies for low-cost fiber-optic data transmission links. Previous authors have recognized the need for low-cost links. By contrast, there has been little written of the trade-offs in link cost/performance among the extant cost-effective fiber-optic technologies. A key cost reducing step can be made by employing large-core fiber (LCF) to allow less-precise alignment tolerances in the optical subassemblies (OSA) and connectors. The fiber-optics industry has recognized this and has responded by making available a myriad of LCF available to the link designer including glass and plastic step-index (SI) and graded index (GI) fibers in a range of diameters and numerical apertures. We will show, however, that the fiber choice and coupling optics design are constrained both by transmitter and receiver coupling efficiency and link bandwidth. The particular type of LCF will also determine the appropriate optical source wavelength, which can greatly impact link cost, bandwidth, and optical budget. Along with reducing the OSA cost, LCF also allows a reduction in connectorization cost and offers a link less susceptible to mode-selective loss noise. This study is summarized by a comparison of component costs, link budgets, and performance limits of both standard and low-cost fiber-optic technologies.