Micromachined interferometric and atomic sensors enabled by integrated thin film optics.

摘要

In this thesis, thin film optical techniques as applied to micromachined devices with optical detection are explored for the formation of high precision sensors. Specifically, two micromachined optical MEMS devices are introduced, fabricated, and characterized. The first is an accelerometer based on parallel plate Fabry-Perot interferometers. The second is a vapor cell for use in chip scale atomic MEMS sensor applications. Both devices are fabricated using bulk micromachining with integrated thin film reflectors. A single axis Fabry-Perot accelerometer with integrated thin film reflectors is designed, fabricated and demonstrated to have a resolution better than 1 mu g/ Hz at a frequency of 2 kHz. The effect of squeeze film constriction in such devices is characterized in similar devices and shown to be capable of extending the sensor bandwidth by as much as 48% over ideally vented designs. Two thin film reflector techniques are demonstrated to form wavelength dependant reflectors that allow the serialization of Fabry-Perot accelerometers into linear serial arrays based on the wavelength division multiplexing of the optical signals. A linear array of two optically multiplexed devices is demonstrated. Similar multilayer reflectors are integrated onto the angled interior sidewalls of an atomic MEMS vapor cell to improve the optical return performance by as much as seven times. The techniques is demonstrated to be compatible with the encapsulation of the 87Rb isotope. Advanced reflector designs are introduced to overcome the challenges of integrating multilayer reflectors into the micromachined cavities forming the vapor cells.