Spatial and temporal laser pulse shaping for two color excitation

Abstract

Spatial and temporal laser pulse shaping is reported for two adjacent ranges of the laser spectrum. Thereto, two-photon excited fluorescence of dyes is measured for tailored pulses having two different spectral components which possess differently modulated spatial shapes. These particularly designed pulses are formed by using a 4f-temporal liquid crystal pulse shaper followed by a 2D-spatial shaper setup. Increased fluorescence contrasts between different dyes in a cuvette are recorded by selective phase shaping of the two adjacent spectral components. Moreover, two-photon excitation of the two spectral ranges from partially overlapping beams leads to spatially localized fluorescence in the overlap region. This is controlled by utilizing antisymmetric phase functions and can be applied to yield more complex two-photon excited fluorescence structures. The developed temporal and spatial shaping method of two-photon processes has valuable perspectives for optical and biophotonic applications.