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Proceedings Paper

Fabrication of f/0.7 GaP microlens arrays by accelerated mass-transport smoothing in sealed ampoules
Author(s): James S. Swenson Jr.; Margaret H. Abraham; Renny Arthur Fields
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Paper Abstract

GaP lens arrays have been routinely produced in large formats (substrate dimensions up to 1.5 by 1.0 cm) with high yield and uniformly good finish. Diffraction-limited performance for collimation of single-mode diode lasers has been demonstrated. Laser-diode bars and coherent 2-D surface-emitting arrays have also been collimated with low transmission losses (98%) for 2.5 micrometers > (lambda) > 0.8 micrometers . Microlenses up to 300 micrometers in diameter with f/#s as low as 0.7 have been enabled by a new mass transport fabrication technique using sealed quarts ampoules rather than a flowing tube furnace. In this modification only small pieces of phosphorus are required (no phosphine or hydrogen); consequently, little safety burden is incurred, and initial expenses are reduced. The mesa-step-spacing was increased from 10 micrometers to 15 micrometers , and, by additional chemistry control, 30 micrometers spacings have been demonstrated. Also, time-at-temperature for mass-transport smoothing has been shortened to as little as 8 h. Mass-transport chemical mechanisms and material incompatibilities are discussed. Smoothing in the fused-quartz ampoules is shown to be self- terminated by wafer oxidation, probably caused by oxygen from thermal equilibrium dissociation of the silicon dioxide ampoule. This mass transport technique lends itself to a wide variety of novel lens fabrication strategies and clearly extends the potential applications.

Paper Details

Date Published: 12 May 1995
PDF: 6 pages
Proc. SPIE 2383, Micro-Optics/Micromechanics and Laser Scanning and Shaping, (12 May 1995); doi: 10.1117/12.209034
Show Author Affiliations
James S. Swenson Jr., The Aerospace Corp. (United States)
Margaret H. Abraham, CT Engineering Corp. (United States)
Renny Arthur Fields, The Aerospace Corp. (United States)

Published in SPIE Proceedings Vol. 2383:
Micro-Optics/Micromechanics and Laser Scanning and Shaping
M. Edward Motamedi; Leo Beiser, Editor(s)

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