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Abstract: This paper reports on the design and implementation of high efficiency, nonmetallic reflectors integrated on the sidewalls of micromachined cavities. Due to shadowing from deposition within a cavity, significant variation in the thicknesses of the dielectric thin films composing the reflectors are encountered when the layers are deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD). These gradients in thickness limit the performance of the reflector at the intended design wavelength. An optimized design procedure is described to maximize the performance of the reflector at the absorption wavelength of of 795nm for use in micromachined atomic vapor cells. The reflector design is based on multiple shifted quarter wave Bragg reflectors in series, which extends the reflective bandwidth for increased robustness to film thickness gradients. The extended reflectance range maintains high reflection at the design wavelength despite greater than 70% decrease in film thickness across the reflector surface. The reflector technology is ideally suited for use in atomic MEMS vapor cell applications by achieving high reflectance while maintaining light polarization. We demonstrate less than 2dB of return loss with circular polarization ellipticity maintained to . [Copyright &y& Elsevier]

Abstract: This paper reports on a method for improving the optical efficiency of micromachined reflectors integrated in rubidium vapor cells for application in atomic MEMS sensors. A hybrid bulk micromachining and multilayer PECVD thin film process is used to form the Bragg reflectors on angled sidewalls, which redirect laser light through the vapor cell and back toward the plane of the source with reduced optical power loss. Integrated thin film Bragg reflectors are shown to improve the reflectance of the micromachined surface by almost three times, resulting in an optical return efficiency of two paired dielectric reflectors that is as much as eight times higher then uncoated silicon reflectors. Absorption of the absorption line at a wavelength of 795nm in a 1 vapor cell is demonstrated experimentally by use of two integrated thin film reflectors with a total optical return efficiency approaching 40%. [Copyright &y& Elsevier]