Latest article: enhanced two-photon excitation of fluorescence
Two-photon excitation of single fluorescent molecules has generated much interest and expectations, especially for analytical sciences. However, current demonstrations struggle with low two-photon fluorescence rate per molecule and/or high background. In a recent publication in Biomedical Optics Express, we answer these challenges by using a single polystyrene microsphere under focused Gaussian illumination. This opens new opportunities to extend the applications of two-photon fluorescence detection.
1- We demonstrate a simple, robust, and low-cost solution to enhance the two-photon fluorescence signal per molecule up to one order of magnitude, without adding any significant photoluminescence noise. This goes significantly beyond the current state-of-the-art.
2- We perform a thorough characterization of the two-photon fluorescence enhancement in the vicinity of a single dielectric microsphere, and report 30x higher fluorescence enhancement factors than earlier work in the field.
3- The microspheres form an interesting structure to compare the gains in one- and two-photon excitation of fluorescence. Such comparison has been seldom reported in the litterature.