Promotionsvortrag Physik: Visualization of intra-cavity dynamics of high-quality factor microresonators

Ankündigung des Promotionsvortrags von: Herrn Haochen Yan

Whispering-gallery-mode (WGM) microresonators are powerful platforms for nonlinear optics and light-matter interactions because they combine optical confinement, ultra-low loss, and high quali-ty factors. These properties support phenomena such as frequency comb generation, Raman las-ing Brillouin scattering, and spontaneous symmetry breaking. However, conventional transmission and reflection measurements provide only indirect and spatially averaged information, limiting ac-cess to intra-cavity dynamics.

In this talk, I present a visualization method based on collecting scattered light from WGM micro-resonators with a short-wave infrared (SWIR) camera. This approach enables observation of spa-tial evolution of resonant modes beyond spectral measurements. I show how this imaging frame-work reveals standing-wave formation, Kerr comb dynamics, cascaded Brillouin processes, and spontaneous symmetry breaking, and how the observed patterns can be analyzed quantitatively to distinguish different dynamical regimes.

I also present a simplified fabrication strategy for high-Q aluminum nitride microresonators based on a single silicon nitride hard mask and conductive polymer. This method avoids a metal mask while still achieving intrinsic quality factors up to 10^6 and enabling strong nonlinear effects. Over-all, the dissertation combines device fabrication, nonlinear photonics, and optical diagnostics, and points toward applications in sensing, defect characterization, and photonic control.

(Vortrag auf Englisch)

Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind öffentlich. Diesen Verfahrensteilen folgt ein nicht öffentliches Rigorosum von 45 Minuten.