| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 105 === In this studies, we focused on designing resonant cavities by various reflectors, including Bragg reflector, grating reflector, high-index-contrast grating and periodic small resonant cavities employed on acoustic cavities. We compare the differences between different reflectors. Different from our intuitive thinking, the reflectors don’t need to cover the entire cavity surface. Even though the surface of reflection is full of holes, sometimes the area of holes is more than half of total area, we can still use the principle of side coupling to design resonant cavities.
In EM wave, resonant cavities are all composed of dielectric, which has smaller loss compared to metal. Compared to traditional dielectric resonant cavities, which use the index difference to confine energy in the dielectric, in this work, we use dielectric as reflectors and confine energy in the air. The benefits of doing so is to prevent the nonlinear effect caused by high energy and prevent the breakdown of dielectric. Hence, the cavities designed in this work can contain higher energy.
In acoustic wave, we use the structure of Buckyball to arrange our small cavities and prove that even the periodicity is not very good, we can still realize spherical resonator.
We’ll start from the characteristics of each reflector and their frequency response, and then design simple one dimensional cavities. Afterwards, we circle the one dimensional reflector to design two dimensional resonant cavity. If there is a k vector component along the traveling direction, then we can design waveguide, however, this is beyond the scope of this work. Finally we arrange the small cavities along the surface of spherical shell, we can design three dimensional resonant cavities.
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