Optical Parametric Oscillation in Magnesium Fluoride Microresonators

Abstract

In this Thesis, we work with magnesium uoride (MgF2) microresonators to demonstrate widely tunable parametric oscillation. Theoretical investigations are presented, which are then supported numerically and experimentally. We begin by fabricating our MgF2 microresonators, detailing our methodology starting from monolithic blanks to the nal design. We give descriptions on our shaping, polishing, and cleaning techniques which we found consistently produced high nesse resonators and following our method, present two of our fabricated MgF2 resonators. The optical quality of these resonators are then quanti ed by measuring their nesse. We then experimentally demonstrate optical parametric oscillation in our microresonators, and present our scheme for wideband tunability with the parametric sidebands. The tuning capabilities are characterised with both of our resonators, showing excellent agreement with the theoretical models. The full extent of the tuning is shown by operating at the end of C-band which resulted in parametric sidebands being observed almost an octave apart. The long wavelength sideband is shifted from 1530nm to 2227nm which is the start of the mid-infrared region. Finally we investigate a recently reported phenomenon whereby localised comb structures form about the pump and parametric sidebands in Kerr microresonators, coined as clustered frequency combs. We do this by presenting theoretical arguments on the origin and dynamics of these comb clusters, and present numerical simulations that reinforce this theory. Furthermore we experimentally characterise key development stages of these clusters, and compare our results with the standard theory of comb formation in Kerr microresonators.