Polarization enhanced two-photon excited fluorescence contrast by shaped laser pulses using a deformable phase plate

Abstract

We utilize spatially and temporally tailored laser pulses for polarization enhanced two-photon excited fluorescence contrasts of dyes. The shaped laser pulses are produced by first passing through a temporal pulse shaper and then through a two-dimensional spatial pulse shaper with deformable phase plates. Different spatial beam profiles are presented that demonstrate the potential of the spatial pulse shaper. Particularly, a polarization enhanced fluorescence contrast between two dyes is reported by utilizing specific phase shaping in perpendicular polarization directions. The tailored laser pulses are further modified by the deformable phase plate, and a polarization increased depth-dependent contrast is achieved. This spatial shaping for all polarization directions demonstrates the advantage of deformable phase plate spatial shapers compared to liquid crystals, where only one polarization direction can spatially be modified. The described polarization contrast method allows for three-dimensional scanning of probes and provides perspectives for biophotonic applications.