Resonators made of a disk and a movable continuous-membrane

Abstract

Microcavities are used for resonantly enhanced interactions of light with matter or particles. Usually, the resonator’s sensitivity drops down with every particle attached to its interface due to the inherent scattering losses and the corresponding degradation of the optical quality factor. Here, we demonstrate, for the first time, a hybrid resonator made of a dielectric disk and a continuous membrane. The membrane is evanescently coupled to the disk while both membrane and disk are mechanically separated. Therefore, the optical mode is co-hosted by the disk and the membrane, while we use a nanopositioning system to control the disk motion. We experimentally demonstrate that spreading scatterers on the membrane and then moving the membrane parallel to the disk brings different scatterers into and out of the optical-mode region. We also show that the membrane’s motion toward the disk results in a 35 GHz drift in the optical resonance frequency. The membrane is continuous in two dimensions and can move a practically unlimited distance in these directions. Furthermore, the membrane can move from a state where it touches the disk to an unlimited distance from the disk. Our continuum-coupled resonator might impact sustainable sensors where the perpetual motion of analytes into and out of the optical-mode region is needed. Additionally, the membrane can carry quantum dots or point defects such as nitrogen-vacancy centers to overlap with the optical mode in a controllable manner. As for non-parallel motion, the membrane’s flexibility and its ability to drift resonance frequency might help in detecting weak forces.