Ramon Lane

Coupling efficiency of a batch-aligned laser-fiber array

Coupling efficiencies for 32-wide, batch-aligned arrays of laser-fiber interconnects were measured and compared to the efficiency obtainable with individual alignment. The tests were carried out using 1300 nm, InP ridge lasers and Corning SMF-28, single-mode optical fibers. In this paper, the associated fabrication and alignment techniques are described briefly. Results are given showing how coupling efficiency depends on misalignment, on laser-to-fiber distance, on fiber bevel angle, and on piece-to-piece variations among lasers and fibers. A direct comparison of batch alignment versus individual alignment is also given, which shows that the average batch-aligned efficiency is about 88 percent as large as the individually aligned (optimal) efficiency. This result, which reflects a particular packaging methodology and best-effort alignment, gives a good indication of the coupling efficiencies which may be typically expected for wide, batch-aligned arrays.

Forty dot/millimeter resistive ribbon thermal print head

A key element to printing high resolution grey level images using resistive ribbon thermal printing technology, is the ability to fabricate a high density electrode print head. To print at 40 dots/mm resolution, the print head electrodes have to be on 25 im centers. Each electrode having a width of 15 to 17 /im. Wet etching techniques can not etch such structures in 25 thick tungsten. A reactive ion etching process suitable for manufacturing high resolution print heads from a tungsten sheet has been developed. Various system parameters were studied, such as gas mixtures, system vacuum pressure and applied RF power, with the goal of achieving an optimum etching process. The results identified SF6 based gas mixtures as the most suitable candidate for high volume removal of tungsten with an acceptable etch rate and edge profile. To study the print quality at 40 pel/mm, other parameters such as ink ribbon and paper surface finish were also investigated. An ink layer thickness and a paper were selected to match the quality of the high resolution print head. The electric power requirements to print single pel features repeatedly was studied.