Fabrication and infrared-transmission properties of a free-standing monolayer of hexagonal-close-packed dielectric microspheres

This paper presents a self-supporting technique for fabricating a free-standing monolayer (FSM) of hexagonal-close-packed (HCP) polystyrene (PS) microspheres, based on a combination of Langmuir-Blodgett method and a robust transferring technique. Three narrow bandwidth resonances (NBRs) with quality factors as high as 142 are experimentally observed for the first time in the transmission spectra of the FSM of 1.0-μm-diameter PS spheres. Further numerical simulations confirm that these NBRs supported by the FSM originate from the excitations of photonic eigenmodes of the array. In addition, these NBRs are experimentally demonstrated to be highly tunable by simply changing the size of PS microsphere. Moreover, we further demonstrate both by experimentally and theoretically that the incorporation of a dielectric substrate to the monolayer of HCP dielectric microspheres have adverse effect on obtaining high-Q resonances compared to the free-standing case, i.e., broaden the linewidths and decrease the amplitudes of the observed resonances.