10 September 2013 Combination of guided mode and photometric optical metrology methods for precise determination of refractive index dispersion: application to polymer blend and ceramic thin films for gas sensors
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Optical Engineering, 52(9), 094104 (2013). doi:10.1117/1.OE.52.9.094104
Abstract
Two optical techniques, m-lines and spectroscopic ellipsometry, are compared for their suitability for obtaining the wavelength and the temperature dispersion of the refractive index of thin-film layers used in gas detector devices. Two types of materials that are often integrated into gas sensors are studied: a polymer organic–inorganic blend deposited by spin coating typically used in near-infrared waveguides and the ceramic semiconductor SrTi 1−x Fe x O 3 (strontium titanate) doped with iron at concentrations x=0.075 and 0.1 deposited by electron beam deposition. The refractive index dispersion obtained by m-lines and ellipsometry is compared, and the differences between the measured parameters for the two materials are discussed. The chromatic dispersion will be represented by a three-term Cauchy law. An intuitive method for verifying the measured indices using an integrating sphere and reflexion coefficient modeling techniques are also demonstrated. Thermo-optic coefficients in the order of −1×10 −4 /K for both materials are reported, and very low chromatic dispersions are also measured, thanks to the high sensitivity of the m-lines technique. The uniaxial anisotropic properties of the polymer-blend films are measured and discussed in the case of the semiconductor films.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Thomas M. Wood, Judikaël Le Rouzo, François R. Flory, Paul Coudray, Valmor R. Mastelaro, Pedro Pelissari, Sérgio C. Zilio, "Combination of guided mode and photometric optical metrology methods for precise determination of refractive index dispersion: application to polymer blend and ceramic thin films for gas sensors," Optical Engineering 52(9), 094104 (10 September 2013). http://dx.doi.org/10.1117/1.OE.52.9.094104
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KEYWORDS
Refractive index

Dispersion

Polymers

Ceramics

Thin films

Ellipsometry

Iron

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