Photolithographed Whispering Gallery Mode Microdisk Cavities Coupled to Semiconductor Quantum Dots

The development of whispering gallery mode (WGM) cavities as integrated light sources and sensors requires a scalable, low-cost fabrication of high-quality microcavities with integrated light sources. In particular, semiconductor quantum dots (QDs) are promising nanoemitters with highly desirable photostability and tunable optical properties, but their controlled coupling to polymeric microcavities is hampered by chemical incompatibility between the QD surface ligands and the high refractive index polymers used to fabricate microcavities. In this paper, we present a new type of polymeric WGM microdisk cavity realized by photolithography on an industrial photosensitive epoxy resin. We demonstrate the homogeneous labeling of these microcavities by CdSe/CdS/Zns QDs, thanks to a novel surface ligand and the coupling of their emission to WGMs from the microdisk cavity. The spectral properties of the WGM-coupled emission are consistent with electromagnetic simulations and indicate that the WGM quality factors can reach values higher than 6000. This demonstrates that the photolithography of high refractive epoxy resins followed by the integration of functionalized QDs enables the realization of well-controlled, high-quality WGM microresonators.