الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Highly reflective micromirrors have been in high demand in recent decades, due to their usage in many systems, such as optical resonators, optical scanners, lab-on-chip spectrometers, and optical switches. One specific application – gas analyzers based on spectrometers – is employed in healthcare and environmental applications. Light interactions with different gases enable gas identification and quantification. The absorption of specific spectral lines from a wide-spectral input creates a unique spectral print for every gas. For gases of weak absorption, the light can be directed to propagate through the gas multiple times using numerous mirror reflections within confined cell structures. The increasing demand for miniaturization and compact lab-on-chip solutions inspired the use of microfabricated structures for gas analyzers and other gas sensing applications. In this context, vertical micromirrors are used to create gas cells and are thus required to exhibit highly reflective abilities.
In our work, metallized vertical micromirrors, which are metallized using sputtering process, are modeled and compared to ideal metal-coated mirrors. The study takes in consideration the structure variations due to the metallization process, such as the variation of the coating depth and the porosity of the resulting sputtered coating which affect the overall mirror performance. A physical model is developed to show the reflectivity of the fabricated micromirrors with an optical model based on the multilayer matrix method and the effective medium theory. The model considers different illumination conditions and reports the results and comparisons with perfect reflection cases. Then, a multilayer coating design is presented to overcome the degradation in the reflectivity values from the metallization. Lastly, a multipass cell design is presented for integration with miniaturized gas spectrometers. Analytical expressions are derived for the total path length and maximum angle of optical incidence. The performance of the cell is compared for cylindrical and spherical mirrors using ray tracing tools.