Microdisk cavities with a Brewster notch

In a recent paper [J. Kullig, X. Jiang, L. Yang, and J. Wiersig, Phys. Rev. Res. 2, 012072(R) (2020)], the authors reported on an alternative concept to confine light in a microdisk cavity which is based on sequential transmissions at Brewster's angle. In this paper, we combine that approach with the traditional concept of whispering-gallery microcavities which utilize total internal reflection. This allows for a notched cavity design promoting high-Q modes which are conventionally excitable via an attached waveguide and have a considerable fraction of the intensity confined in the notch. The interesting mode characteristics as well as the excellent sensing capability of the Brewster notched cavity is discussed. A further enhancement in the sensitivity is achieved via the utilization of an exceptional point.