Tunability and synthetic lineshapes in high-Q optical whispering gallery modes

摘要

We demonstrate novel techniques to manipulate spectral properties of high quality factor (Q > 10~7) whispering-gallery modes (WGM) in optical dielectric microresonators. These include permanent frequency trimming of WGM frequencies by means of UV photosensitivity of germanium doped silica resonators; electro-optical tuning of WGM in lithium niobate resonators, and cascading of microresonators for obtaining second-order filtering function. We present theoretical interpretation of experimental results, and examples of applications of these techniques for photonic microwave filtering.