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Proceedings Paper

Multispectral reflectance-mode fiber optic deposition rate monitor
Author(s): James T. Daly; John A. Wollam; Fei Luo; Theodore F. Morse; Andreas Kussmaul; Dan Pulver
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Paper Abstract

We have developed and demonstrated a reflection-mode optical fiber-based instrument for in situ monitoring and feedback control of thin film dielectric deposition processes. The instrument operates in single-wavelength or multi-wavelength mode. One end of the fiber is placed in the deposition zone, close to the samples being coated. Single or multi-wavelength light is sent down the fiber and the reflected light from the end being coated is analyzed for intensity vs. wavelength. The fiber end being coated features an easily replaced tip to prevent loss of resolution when the coating becomes too thick. For processes in which the index of refraction or composition of the thin films is fixed, the less expensive single wavelength instrument is sufficient and measures thickness of the films by counting interference fringes. For processes in which film composition or index of refraction are variable, we use a white light source and compact spectrograph to measure reflectance vs. wavelength. For critical applications like diode laser facet coating where yield loss is significant cost driver, this monitor measures the thickness and index of refraction of single and multi-layer thin films as they are deposited. More importantly, it measures the critical parameter of interest: reflectance at the actual laser emission wavelength. This instrument replaces quartz crystal oscillators and other, more complex instruments.

Paper Details

Date Published: 17 April 2000
PDF: 8 pages
Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, (17 April 2000); doi: 10.1117/12.382831
Show Author Affiliations
James T. Daly, Ion Optics, Inc. (United States)
John A. Wollam, Ion Optics, Inc. (United States)
Fei Luo, Boston Univ. (United States)
Theodore F. Morse, Boston Univ. (United States)
Andreas Kussmaul, Lasertron, Inc. (United States)
Dan Pulver, Lasertron, Inc. (United States)

Published in SPIE Proceedings Vol. 3938:
Light-Emitting Diodes: Research, Manufacturing, and Applications IV
H. Walter Yao; Ian T. Ferguson; E. Fred Schubert, Editor(s)

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