Locally controlled two-photon excited fluorescence by correlated ultrafast intensity fluctuations

Abstract

Abstract We propose a method for improving the imaging depth of two-photon excitation microscopy using correlated ultrafast intensity fluctuations within pulses. As a proof of principle, we experimentally demonstrate local control of two-photon excitation by using the ultrafast intensity cross-correlation generated by high-gain parametric down-conversion. We show that only the fluorescence intensity emitted from deep inside the fluorescent dye solution can be modulated by harnessing the correlation at ultrashort time scales. It is expected that the influence of the background photons can be suppressed by applying this technique to the two-photon excitation microscopy.