Research On The Principle And Application Of MOEMS Accelerometer Based On Microfiber Loop Resonantor

This dissertation presents a novel MOEMS (Micro-Optical Electronical Mechanical System) accelerometer based on microfiber loop resonantor. Microfiber is a new type of waveguide wires with the diameters on the micro, even nanometer scale, and the characteristics of this microfiber are different from both conventional optical fibers and integrated optical waveguide structures. The microfiber loop resonantor, which is coupling by optical evanescent wave in the coupling region, and has shown the low-loss and high Q factor, so this resonator can be used for high sensitivity optical sensor devices. Moreover, the MOEMS accelerometer which combines microfiber technology with silicon MEMS (Micro-ElectroMechanical System) technology is presented in this dissertation.At the beginning of this dissertation, we introduced the background of this subject, and made a comparison with various kinds of MEMS and MOEMS accelerometers. The research object,main contents and novel ideas of this work were also introduced.As the microfiber is an important part of this MOEMS accelerometer. we analysed the principle of the transmission and physical characteristics of the microfiber, which is essential for the microfiber fabrication and application. The research of the mirofiber loop resonantor demonstrated that the Q-factor of microresonantors created by microfibers could potentially compete with the extremely high-Q and much low-loss whispering gallery mode microcavities.As the microfiber loop resonantor can be used for high sensitivity optical sensor devices, we designed a novel MOEMS accelerometer which based on this microfiber loop resonantor and silicon MEMS structure. We provided the sensing process and mathematical mode of this device, and analyzed its performances as well as the signal detecting methods.We also made much effort to the fabrication of the MEMS sensing structure. Firstly, we designed the geometry parameters of the MEMS structure. Secondly, we made the FEA (Finite Element Analysis) analysis of the design by ANSYS. At last, the MEMS acceleration sensing structure was designed, and fabricated by double-faced KOH anisotropic etching with epoxy polymer protecting.After the MEMS structure fabrication, we cemented the microfiber loop resonantor under a microscopical manipulation system, and tested the performances of this MOEMS accelerometer with the transmission spectrum in high-g driving, optical intensity sensitivity in gravity field, dynamic response and temperature effect. The test results demonstrated that this MOEMS accelerometer could support more than 30g acceleration load and its static optical intensity sensitivity is about 624.7mV/g, which is related to Q-factor of the microfiber loop resonantor and MEMS structure parameters. Along with the improvement of Q-factor from 10~3 to 10~6 in the future, the MEMS structure parameters would be optimized through experiments, this MOEMS accelerometer could achieve thousandfold intensity of detecting sensitivity.