Enhancing the radiative decay rate of fluorescent organic molecules using micropillar microcavities and optical nanocavities

We discuss the enhancement of spontaneous emission of fluorescent organic dyes when placed in micropillar microcavities and also in an optical nanocavity. We show experimentally that an enhancement in the spontaneous-emission rate of 1.78 ± 0.04 times can be realized by placing a thin-film of the molecular dye Lumogen Red dispersed in a polymer matrix into a 3 μm diameter micropillar having a Q-factor of 680. We then model the optical properties of Noda nanocavities in vertically symmetric and asymmetric slab waveguides using TiO2 as a high-index dielectric, with the cavity mode wavelength tuned to 713 nm. We estimate that such cavities will have a maximum Q-factor of 4455 and a Purcell Factor (maximum enhancement in the spontaneous-emission rate) of 340.