Theoretical And Experimental Research On Microfiber Mechanical Resonator

Cavity optomechanics,which mainly studies the interaction between the optical field in the cavity and the mechanical resonator,not only provides a broad platform for basic physics research,but also plays an important role in ultra-sensitive sensing and quantum information processing.As the development of micro-nano-machining technology,cavity optomechanics has grown rapidly in recent years.Then,various mechanical resonators as the objects to interact with optical field have been proposed.This dissertation is devoted to theoretical and experimental research on the mechanical resonator in the cavity optomechanics system.The main content is divided into the following three parts:Firstly,we briefly introduce the doubly clamped micro-beam resonator,which is the basis of the micro-beam mechanical resonator.We have described the mechanical vibration model of the micro-beam resonator,and systematically analyzed the loss mechanisms and optimization schemes of the resonator.The second part mainly focuses on the theoretical and experimental research of the proposed novel microfiber mechanical resonator.We established the theoretical model of fiber mechanical resonator,showed its experimental preparation process,and proposed novel optimization scheme.By designing abrupt junctions between the microfiber and single mode fibers and imposing high axial stress in the resonator,the clamping loss is decreased effectively and the resonator material's intrinsic dissipation is also diluted.Ring-down measurements at room temperature show that the quality factors Q of the fundamental and higher-order mechanical modes of the microfiber resonators exceed 10⁵ to yield the highest mechanical f × Q products(>10¹⁰Hz)yet reported for fiber-optic mechanical resonators.Moreover,compared to the traditional fiber string resonator,the microfiber resonator has at least one or two orders magnitude lighter,which will lay an excellent foundation of higher optomechanical coupling strength.After that,we applied this doubly clamped microfiber resonator to ultrasensitive sensing.The common fiber optic torsion sensors are mainly based on fiber gratings and interferometers.In this paper,we propose and experimentally demonstrate a novel sensing mechanism based on a mechanical resonator for torsion measurement.Experimental and theoretical results show that the torsion angle could be measured by monitoring the resonant frequency shift of the mechanical resonator,and the highest sensitivity of the sensor tested in our experiments is 63 Hz/?rad/m?.This compact torsion sensor is immune to electromagnetic interferences and particularly suitable for applications in harsh environments.