Fabrication of polymer microsphere-based whispering gallery mode microcavities of various sizes incorporating AG–IN–S quantum dots

The presented methodology describes the fabrication of active spherical microresonator structures with whispering gallery modes, based on polystyrene microspheres and AgInS$_2$ quantum dots. These microresonators were obtained through electrostatic layer-by-layer deposition in aqueous suspensions. The ability to precisely tune the luminescent response of the active microresonators by adjusting the size of the polystyrene microsphere template is demonstrated. This size-dependent tunability of the optical properties makes these structures highly promising for integration into sensor devices, where optimized performance can be achieved through tailored resonator design.