Fabrication of f/0.7 GaP microlens arrays by accelerated mass-transport smoothing in sealed ampoules

James S. Swenson Jr.; Margaret H. Abraham; Renny Arthur Fields

doi:10.1117/12.209034

12 May 1995 Fabrication of f/0.7 GaP microlens arrays by accelerated mass-transport smoothing in sealed ampoules

James S. Swenson Jr., Margaret H. Abraham, Renny Arthur Fields

Proceedings Volume 2383, Micro-Optics/Micromechanics and Laser Scanning and Shaping; (1995) https://doi.org/10.1117/12.209034
Event: Photonics West '95, 1995, San Jose, CA, United States

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.

Citation Download Citation

James S. Swenson Jr., Margaret H. Abraham, and Renny Arthur Fields "Fabrication of f/0.7 GaP microlens arrays by accelerated mass-transport smoothing in sealed ampoules", Proc. SPIE 2383, Micro-Optics/Micromechanics and Laser Scanning and Shaping, (12 May 1995); https://doi.org/10.1117/12.209034

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