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Design and Demonstration of PECVD Angled Multilayer Dielectric Mirrors Optimized for Micromachined Cavity Sidewalls



M.A. Perez, John Kitching, A Shkel


This paper reports on the design and implementation of high efficiency, non-metallic 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 using 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 D1 absorption wavelength of 87Rb of 795 nm under the variations in material thickness for use in a micromachined atomic vapor cells. The reflector design is based on multiple shifted quarter wave Bragg reflectors in series, which extend 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 1.5 dB of return loss with circular polarization ellipticity maintained to ±2°.
Sensors and Actuators A-Physical


atomic MEMS, vapor cells, optical MEMS, Bragg reflector, thin films, PECVD, magnetometer, gyroscope


Perez, M. , Kitching, J. and Shkel, A. (2008), Design and Demonstration of PECVD Angled Multilayer Dielectric Mirrors Optimized for Micromachined Cavity Sidewalls, Sensors and Actuators A-Physical, [online], (Accessed June 14, 2024)


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Created October 24, 2008, Updated October 12, 2021