Enhanced two-photon excited fluorescence by ultrafast intensity fluctuations from an optical parametric generator

Abstract

We evaluate the enhancement of two-photon excited fluorescence from fluorescent dye by ultrafast intensity fluctuations of light generated by a nanosecond optical parametric generator (OPG). By modifying the well-established techniques for measuring the second-order coherence on ultrashort timescale, we observed the enhancement of the fluorescence from Rhodamine B dye by a factor of two due to the bunching effect of light. A nanosecond OPG can be built at a much lower cost than the ultrashort pulse used in two-photon excitation microscopes. Therefore, our work paves the way toward a low-cost and efficient nonlinear microscope.