Combined wavelength and frequency modulation spectroscopy: A novel diagnostic tool for materials processing

Document Type

Article

Publication Date

2-20-1993

Abstract

By applying both low-frequency wavelength modulation and high-frequency phase modulation to a laser diode, we develop a sensitive, high-bandwidth chemical diagnostic tool that is applicable to a variety of gas-phase processing environments. Specific chemical species are identified and monitored through their infrared absorption spectra, and the modulation methods allow for sensitive detection that is free of window and other reflection-driven interference fringes. Absorbance limits of 5.3 × 10−8 and 1.9 × 10−7 are obtained for an AlGaAs diode laser and a lead-salt diode laser, respectively. We discuss applications to plasma etching and chemical vapor deposition. © 1993 Optical Society of America.

Identifier

0000215347 (Scopus)

Publication Title

Applied Optics

External Full Text Location

https://doi.org/10.1364/AO.32.000885

e-ISSN

21553165

ISSN

1559128X

First Page

885

Last Page

893

Issue

6

Volume

32

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