Abstract
Resonators have been treated as essential elements in optics because of their capacity to store and enhance light and exhibit a wide range of applications such as semiconductor lasers and optical communication components. In this article, we reveal a new mechanism of light field confinement in an optical cavity composed of different valley photonic crystals. The electromagnetic field of light is localized because of the valley spin states contrasted between the inner and outer regions, which leads a high Q-factor and a small model volume of the resonator. Furthermore, the whispering-gallery-mode modulated vortex phase distribution is demonstrated in the proposed structure, which offers a new method for manipulating the light field. The energy spectrum as well as the light field distributions show the simultaneous appearance of both bulk and edge states. Such effect becomes pronounced or diminished when the domain wall changes, and can be explained by the location of the edge states in the shared bandgap. Our findings offer a novel mechanism of light field confinement and phase modulation, which may pave the way for a new type of topological device and provide broad applications in the areas of micro-lasers, optical communications, and other light-matter interaction systems.
Published Version
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